Category: c Standard Library

C library – <inttypes.h> ”; Previous Next The C library header <inttypes.h> provides various macros for formatting and working with numeric data type(int). These macros are useful when we are using printf() and scanf() function. Library Macros Here, we are going to explore some important key macros of inttypes.h − Macros of output format specifier − printf() function PRIxMAX: This is printf specifier for intmax_t which is equivalent to %x(hexadecimal). PRIiMAX: This is printf specifier for intmax_t which is equivalent to %i(integer). PRIuLEAST32: This is printf specifier for uint_least32_t which is equivalent to %u(unsigned). Macros of input format specifier − scanf() function Similar to printf() function, here are some macros which is used for reading input− SCNxMAX: This is scanf specifier for intmax_t which is equivalent to %x(hexadecimal). SCNiMAX: This is scanf specifier for intmax_t which is equivalent to %i(integer). SCNuLEAST32: This is scanf specifier for uint_least32_t which is equivalent to %u(unsigned). String function Macros Below are list of some macros which supports string function − strtoimax(str, endptr, base): It is equivalent to strtol() for intmax_t. strtoumax(str, endptr, base): It is equivalent to strtoul() for uintmax_t. wcstoimax(wcs, endptr, base): It is equivalent to wcstol() for intmax_t. wcstoumax(wcs, endptr, base): It is equivalent to wcstoul() for uintmax_t. Example 1 Following is C library header <inttypes.h> which provide the program for printing integer value with a fixed width. #include <stdio.h> #include <inttypes.h> int main() { int32_t num1 = 67543; int64_t num2 = 894432590; printf(“Formatted output using inttypes.h:n”); printf(“num1: %” PRId32 “n”, num1); printf(“num2: %” PRId64 “n”, num2); return 0; } Output On execution of above code, we get the following result − Formatted output using inttypes.h: num1: 67543 num2: 894432590 Example 2 Below the program calculate the factorial of a number using unintmax_t under the header inttypes.h. #include <stdio.h> #include <inttypes.h> uintmax_t factorial(uintmax_t n) { if (n == 0) return 1; else return n * factorial(n – 1); } int main() { uintmax_t num = 5; printf(“Factorial of %” PRIuMAX ” = %” PRIuMAX “n”, num, factorial(num)); return 0; } Output After executing the code, we get the following result − Factorial of 5 = 120 Example 3 Below the program reads a 64-bit unsigned integer from the user using SCNu64. It then prints the entered value using PRIu64. #include <stdio.h> #include <inttypes.h> int main() { uint64_t large_number = 9876543210; printf(“The entered number: %” PRIu64 “n”, large_number); return 0; } Output The above code produces the following result − The entered number: 9876543210 Print Page Previous Next Advertisements ”;

C library – <stdbool.h> ”; Previous Next The C library <stdbool.h> header supports the bool data types. The bool can store the value as true(0) or false(1) which is common requirement in various programming languages. There are three ways to perform the implementation of this header − The stdbool.h − This is C header which support the boolean variable. The Enumeration (enum) type − This is special type of data which is defined by the user. This includes either integral constant or integer. Declare the boolean values − The value can be defined as true or false. Example 1 Following is the simple C library header <stdbool> to see the conversion of boolean value in integer form. #include <stdbool.h> #include <stdio.h> int main() { // Declaration of boolean data types bool x = true; bool y = false; printf(“True : %dn”, x); printf(“False : %d”, y); return 0; } Output The above code produces the following output − True : 1 False : 0 Example 2 Below the program create an enumeration(enum) type to represent boolean values explicitly. #include <stdio.h> enum Bool { FALSE, TRUE }; int main() { enum Bool isTrue = TRUE; enum Bool isFalse = FALSE; // Rest of your code… printf(“isTrue: %dn”, isTrue); printf(“isFalse: %dn”, isFalse); // Rest of your program logic… return 0; } Output The above code produces the following output − isTrue: 1 isFalse: 0 Example 3 Here, we directly declare the boolean value using integer constants which shows the 0 for false and 1 for true. #include <stdio.h> int main() { int isTrue = 1; // true int isFalse = 0; // false printf(“isTrue: %dn”, isTrue); printf(“isFalse: %dn”, isFalse); return 0; } Output The above code produces the following output − isTrue: 1 isFalse: 0 Print Page Previous Next Advertisements ”;

C Library – <signal.h> ”; Previous Next The signal.h header defines a variable type sig_atomic_t, two function calls, and several macros to handle different signals reported during a program”s execution. Library Variables Following is the variable type defined in the header signal.h − Sr.No. Variable & Description 1 sig_atomic_t This is of int type and is used as a variable in a signal handler. This is an integral type of an object that can be accessed as an atomic entity, even in the presence of asynchronous signals. Library Macros Following are the macros defined in the header signal.h and these macros will be used in two functions listed below. The SIG_ macros are used with the signal function to define signal functions. Sr.No. Macro & Description 1 SIG_DFL Default signal handler. 2 SIG_ERR Represents a signal error. 3 SIG_IGN Signal ignore. The SIG macros are used to represent a signal number in the following conditions − Sr.No. Macro & Description 1 SIGABRT Abnormal program termination. 2 SIGFPE Floating-point error like division by zero. 3 SIGILL Illegal operation. 4 SIGINT Interrupt signal such as ctrl-C. 5 SIGSEGV Invalid access to storage like segment violation. 6 SIGTERM Termination request. Library Functions Following are the functions defined in the header signal.h − Sr.No. Function & Description 1 void (*signal(int sig, void (*func)(int)))(int) This function sets a function to handle signal i.e. a signal handler. 2 int raise(int sig) This function causes signal sig to be generated. The sig argument is compatible with the SIG macros. Print Page Previous Next Advertisements ”;

C Library – <stdio.h> ”; Previous Next The stdio.h header defines three variable types, several macros, and various functions for performing input and output. Library Variables Following are the variable types defined in the header stdio.h − Sr.No. Variable & Description 1 size_t This is the unsigned integral type and is the result of the sizeof keyword. 2 FILE This is an object type suitable for storing information for a file stream. 3 fpos_t This is an object type suitable for storing any position in a file. Library Macros Following are the macros defined in the header stdio.h − Sr.No. Macro & Description 1 NULL This macro is the value of a null pointer constant. 2 _IOFBF, _IOLBF and _IONBF These are the macros which expand to integral constant expressions with distinct values and suitable for the use as third argument to the setvbuf function. 3 BUFSIZ This macro is an integer, which represents the size of the buffer used by the setbuf function. 4 EOF This macro is a negative integer, which indicates that the end-of-file has been reached. 5 FOPEN_MAX This macro is an integer, which represents the maximum number of files that the system can guarantee to be opened simultaneously. 6 FILENAME_MAX This macro is an integer, which represents the longest length of a char array suitable for holding the longest possible filename. If the implementation imposes no limit, then this value should be the recommended maximum value. 7 L_tmpnam This macro is an integer, which represents the longest length of a char array suitable for holding the longest possible temporary filename created by the tmpnam function. 8 SEEK_CUR, SEEK_END, and SEEK_SET These macros are used in the fseek function to locate different positions in a file. 9 TMP_MAX This macro is the maximum number of unique filenames that the function tmpnam can generate. 10 stderr, stdin, and stdout These macros are pointers to FILE types which correspond to the standard error, standard input, and standard output streams. Library Functions Following are the functions defined in the header stdio.h − Sr.No. Function & Description 1 int fclose(FILE *stream) Closes the stream. All buffers are flushed. 2 void clearerr(FILE *stream) Clears the end-of-file and error indicators for the given stream. 3 int feof(FILE *stream) Tests the end-of-file indicator for the given stream. 4 int ferror(FILE *stream) Tests the error indicator for the given stream. 5 int fflush(FILE *stream) Flushes the output buffer of a stream. 6 int fgetpos(FILE *stream, fpos_t *pos) Gets the current file position of the stream and writes it to pos. 7 FILE *fopen(const char *filename, const char *mode) Opens the filename pointed to by filename using the given mode. 8 size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream) Reads data from the given stream into the array pointed to by ptr. 9 FILE *freopen(const char *filename, const char *mode, FILE *stream) Associates a new filename with the given open stream and same time closing the old file in stream. 10 int fseek(FILE *stream, long int offset, int whence) Sets the file position of the stream to the given offset. The argument offset signifies the number of bytes to seek from the given whence position. 11 int fsetpos(FILE *stream, const fpos_t *pos) Sets the file position of the given stream to the given position. The argument pos is a position given by the function fgetpos. 12 long int ftell(FILE *stream) Returns the current file position of the given stream. 13 size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream) Writes data from the array pointed to by ptr to the given stream. 14 int remove(const char *filename) Deletes the given filename so that it is no longer accessible. 15 int rename(const char *old_filename, const char *new_filename) Causes the filename referred to, by old_filename to be changed to new_filename. 16 void rewind(FILE *stream) Sets the file position to the beginning of the file of the given stream. 17 void setbuf(FILE *stream, char *buffer) Defines how a stream should be buffered. 18 int setvbuf(FILE *stream, char *buffer, int mode, size_t size) Another function to define how a stream should be buffered. 19 FILE *tmpfile(void) Creates a temporary file in binary update mode (wb+). 20 char *tmpnam(char *str) Generates and returns a valid temporary filename which does not exist. 21 int fprintf(FILE *stream, const char *format, …) Sends formatted output to a stream. 22 int printf(const char *format, …) Sends formatted output to stdout. 23 int sprintf(char *str, const char *format, …) Sends formatted output to a string. 24 int vfprintf(FILE *stream, const char *format, va_list arg) Sends formatted output to a stream using an argument list. 25 int vprintf(const char *format, va_list arg) Sends formatted output to stdout using an argument list. 26 int vsprintf(char *str, const char *format, va_list arg) Sends formatted output to a string using an argument list. 27 int fscanf(FILE *stream, const char *format, …) Reads formatted input from a stream. 28 int scanf(const char *format, …) Reads formatted input from stdin. 29 int sscanf(const char *str, const char *format, …) Reads formatted input from a string. 30 int fgetc(FILE *stream) Gets the next character (an unsigned char) from the specified stream and advances the position indicator for the stream. 31 char *fgets(char *str, int n, FILE *stream) Reads a line from the specified stream and stores it into the string pointed to by str. It stops when either (n-1) characters are read, the newline character is read, or the end-of-file is reached, whichever comes first. 32 int fputc(int char, FILE *stream) Writes a character (an unsigned char) specified by the argument char to the specified stream and advances the position indicator for the stream. 33 int fputs(const char *str, FILE *stream) Writes a string to the specified stream up to but not including the null character. 34 int getc(FILE *stream) Gets the next character (an unsigned char) from the specified stream and advances the position indicator for the stream. 35 int getchar(void) Gets a character (an

C Library – <errno.h> ”; Previous Next The errno.h header file of the C Standard Library defines the integer variable errno, which is set by system calls and some library functions in the event of an error to indicate what went wrong. This macro expands to a modifiable lvalue of type int, therefore it can be both read and modified by a program. The errno is set to zero at program startup. Certain functions of the standard C library modify its value to other than zero to signal some types of error. You can also modify its value or reset to zero at your convenience. The errno.h header file also defines a list of macros indicating different error codes, which will expand to integer constant expressions with type int. Library Macros Following are the macros defined in the header errno.h − Sr.No. Macro & Description 1 extern int errno This is the macro set by system calls and some library functions in the event of an error to indicate what went wrong. 2 EDOM Domain Error This macro represents a domain error, which occurs if an input argument is outside the domain, over which the mathematical function is defined and errno is set to EDOM. 3 ERANGE Range Error This macro represents a range error, which occurs if an input argument is outside the range, over which the mathematical function is defined and errno is set to ERANGE. Print Page Previous Next Advertisements ”;

C Library – <assert.h> ”; Previous Next The assert.h header file of the C Standard Library provides a macro called assert which can be used to verify assumptions made by the program and print a diagnostic message if this assumption is false. The defined macro assert refers to another macro NDEBUG which is not a part of <assert.h>. If NDEBUG is defined as a macro name in the source file, at the point where <assert.h> is included, the assert macro is defined as follows − #define assert(ignore) ((void)0) Library Macros Following is the only function defined in the header assert.h − Sr.No. Function & Description 1 void assert(int expression) This is actually a macro and not a function, which can be used to add diagnostics in your C program. 2 static_assert(boolean_expression, message) This macro issues a compile-time diagnostic if the value of a constant expression is false. Print Page Previous Next Advertisements ”;

C Library – <limits.h> ”; Previous Next The C Library limits.h header file defines various properties of the different variable types. The macros defined in this header, limits the values of various variable types like char, int and long. These limits specify that a variable cannot store any value beyond these limits, for example an unsigned character can store up to a maximum value of 255. <limits.h> Library Macros The following values are implementation-specific and defined using the #define directive. However, these values may not be lower than the given ones. Macro Value Description CHAR_BIT 8 Defines the number of bits in a byte. SCHAR_MIN -128 Defines the minimum value for a signed char. SCHAR_MAX +127 Defines the maximum value for a signed char. UCHAR_MAX 255 Defines the maximum value for an unsigned char. CHAR_MIN -128 Defines the minimum value for type char and its value will be equal to SCHAR_MIN if char represents negative values, otherwise zero. CHAR_MAX +127 Defines the value for type char and its value will be equal to SCHAR_MAX if char represents negative values, otherwise UCHAR_MAX. MB_LEN_MAX 16 Defines the maximum number of bytes in a multi-byte character. SHRT_MIN -32768 Defines the minimum value for a short int. SHRT_MAX +32767 Defines the maximum value for a short int. USHRT_MAX 65535 Defines the maximum value for an unsigned short int. INT_MIN -2147483648 Defines the minimum value for an int. INT_MAX +2147483647 Defines the maximum value for an int. UINT_MAX 4294967295 Defines the maximum value for an unsigned int. LONG_MIN -9223372036854775808 Defines the minimum value for a long int. LONG_MAX +9223372036854775807 Defines the maximum value for a long int. ULONG_MAX 18446744073709551615 Defines the maximum value for an unsigned long int. Note that, the above macros help developer to write efficient code that works consistently across different platforms and compilers. Example 1 Following is the basic C Library program to display the range value of various macros under the limits.h header file. #include <stdio.h> #include <limits.h> int main() { printf(“The value of CHAR_BIT: %dn”, CHAR_BIT); printf(“The value of SCHAR_MIN: %dn”, SCHAR_MIN); printf(“The value of SCHAR_MAX: %dn”, SCHAR_MAX); printf(“The value of UCHAR_MAX: %un”, UCHAR_MAX); printf(“The value of CHAR_MIN: %dn”, CHAR_MIN); printf(“The value of CHAR_MAX: %dn”, CHAR_MAX); printf(“The value of MB_LEN_MAX: %dn”, MB_LEN_MAX); printf(“The value of SHRT_MIN: %dn”, SHRT_MIN); printf(“The value of SHRT_MAX: %dn”, SHRT_MAX); printf(“The value of USHRT_MAX: %un”, USHRT_MAX); printf(“The value of INT_MIN: %dn”, INT_MIN); printf(“The value of INT_MAX: %dn”, INT_MAX); printf(“The value of UINT_MAX: %un”, UINT_MAX); printf(“The value of LONG_MIN: %ldn”, LONG_MIN); printf(“The value of LONG_MAX: %ldn”, LONG_MAX); printf(“The value of ULONG_MAX: %lun”, ULONG_MAX); return 0; } Output On execution of above code, we get the following result − The value of CHAR_BIT: 8 The value of SCHAR_MIN: -128 The value of SCHAR_MAX: 127 The value of UCHAR_MAX: 255 The value of CHAR_MIN: -128 The value of CHAR_MAX: 127 The value of MB_LEN_MAX: 16 The value of SHRT_MIN: -32768 The value of SHRT_MAX: 32767 The value of USHRT_MAX: 65535 The value of INT_MIN: -2147483648 The value of INT_MAX: 2147483647 The value of UINT_MAX: 4294967295 The value of LONG_MIN: -9223372036854775808 The value of LONG_MAX: 9223372036854775807 The value of ULONG_MAX: 18446744073709551615 Example 2 In this example, we illustrate the program for finding the minimum and maximum values. #include <stdio.h> #include <limits.h> int main() { int input[] = {89, 5, 21, 10, 45, 31, 98}; int n = sizeof(input) / sizeof(input[0]); // Initialization of macros int min_value = INT_MAX; int max_value = INT_MIN; // loop iteration for min and max value for (int i = 0; i < n; ++i) { if (input[i] < min_value) { min_value = input[i]; } if (input[i] > max_value) { max_value = input[i]; } } // Display the result printf(“Minimum value: %dn”, min_value); printf(“Maximum value: %dn”, max_value); return 0; } Output On execution of above code, we get the following result − Minimum value: 5 Maximum value: 98 Example 3 Below the program initializes limit macros(CHAR_MIN/MAX) to generate the minimum and maximum length of character from the given string. #include <stdio.h> #include <limits.h> #include <string.h> int main() { char* char_input[] = {“RUSSIA”, “UK”, “INDIA”, “NEWYORK”, “INDONESIA”, “DUBAI”}; int num_strings = sizeof(char_input) / sizeof(char_input[0]); // Initialization of CHAR macros int min_length = CHAR_MAX; int max_length = CHAR_MIN; for (int i = 0; i < num_strings; ++i) { int current_length = strlen(char_input[i]); if (current_length < min_length) { min_length = current_length; } if (current_length > max_length) { max_length = current_length; } } printf(“Minimum length of characters: %dn”, min_length); printf(“Maximum length of characters: %dn”, max_length); return 0; } Output The above code produces the following result − Minimum length of characters: 2 Maximum length of characters: 9 Print Page Previous Next Advertisements ”;

C Library – <stdlib.h> ”; Previous Next The stdlib.h header defines four variable types, several macros, and various functions for performing general functions. Library Variables Following are the variable types defined in the header stdlib.h − Sr.No. Variable & Description 1 size_t This is the unsigned integral type and is the result of the sizeof keyword. 2 wchar_t This is an integer type of the size of a wide character constant. 3 div_t This is the structure returned by the div function. 4 ldiv_t This is the structure returned by the ldiv function. Library Macros Following are the macros defined in the header stdlib.h − Sr.No. Macro & Description 1 NULL This macro is the value of a null pointer constant. 2 EXIT_FAILURE This is the value for the exit function to return in case of failure. 3 EXIT_SUCCESS This is the value for the exit function to return in case of success. 4 RAND_MAX This macro is the maximum value returned by the rand function. 5 MB_CUR_MAX This macro is the maximum number of bytes in a multi-byte character set which cannot be larger than MB_LEN_MAX. Library Functions Following are the functions defined in the header stlib.h − Sr.No. Function & Description 1 double atof(const char *str) Converts the string pointed to, by the argument str to a floating-point number (type double). 2 int atoi(const char *str) Converts the string pointed to, by the argument str to an integer (type int). 3 long int atol(const char *str) Converts the string pointed to, by the argument str to a long integer (type long int). 4 double strtod(const char *str, char **endptr) Converts the string pointed to, by the argument str to a floating-point number (type double). 5 long int strtol(const char *str, char **endptr, int base) Converts the string pointed to, by the argument str to a long integer (type long int). 6 unsigned long int strtoul(const char *str, char **endptr, int base) Converts the string pointed to, by the argument str to an unsigned long integer (type unsigned long int). 7 void *calloc(size_t nitems, size_t size) Allocates the requested memory and returns a pointer to it. 8 void free(void *ptr Deallocates the memory previously allocated by a call to calloc, malloc, or realloc. 9 void *malloc(size_t size) Allocates the requested memory and returns a pointer to it. 10 void *realloc(void *ptr, size_t size) Attempts to resize the memory block pointed to by ptr that was previously allocated with a call to malloc or calloc. 11 void abort(void) Causes an abnormal program termination. 12 int atexit(void (*func)(void)) Causes the specified function func to be called when the program terminates normally. 13 void exit(int status) Causes the program to terminate normally. 14 char *getenv(const char *name) Searches for the environment string pointed to by name and returns the associated value to the string. 15 int system(const char *string) The command specified by string is passed to the host environment to be executed by the command processor. 16 void *bsearch(const void *key, const void *base, size_t nitems, size_t size, int (*compar)(const void *, const void *)) Performs a binary search. 17 void qsort(void *base, size_t nitems, size_t size, int (*compar)(const void *, const void*)) Sorts an array. 18 int abs(int x) Returns the absolute value of x. 19 div_t div(int numer, int denom) Divides numer (numerator) by denom (denominator). 20 long int labs(long int x) Returns the absolute value of x. 21 ldiv_t ldiv(long int numer, long int denom) Divides numer (numerator) by denom (denominator). 22 int rand(void) Returns a pseudo-random number in the range of 0 to RAND_MAX. 23 void srand(unsigned int seed) This function seeds the random number generator used by the function rand. 24 int mblen(const char *str, size_t n) Returns the length of a multibyte character pointed to by the argument str. 25 size_t mbstowcs(schar_t *pwcs, const char *str, size_t n) Converts the string of multibyte characters pointed to by the argument str to the array pointed to by pwcs. 26 int mbtowc(whcar_t *pwc, const char *str, size_t n) Examines the multibyte character pointed to by the argument str. 27 size_t wcstombs(char *str, const wchar_t *pwcs, size_t n) Converts the codes stored in the array pwcs to multibyte characters and stores them in the string str. 28 int wctomb(char *str, wchar_t wchar) Examines the code which corresponds to a multibyte character given by the argument wchar. Print Page Previous Next Advertisements ”;

C Library – <stdarg.h> ”; Previous Next The stdarg.h header defines a variable type va_list and three macros which can be used to get the arguments in a function when the number of arguments are not known i.e. variable number of arguments. A function of variable arguments is defined with the ellipsis (,…) at the end of the parameter list. Library Variables Following is the variable type defined in the header stdarg.h − Sr.No. Variable & Description 1 va_list This is a type suitable for holding information needed by the three macros va_start(), va_arg() and va_end(). Library Macros Following are the macros defined in the header stdarg.h − Sr.No. Macro & Description 1 void va_start(va_list ap, parmN) This macro enables access to variadic function arguments. 2 type va_arg(va_list ap, type) This macro retrieves the next argument in the parameter list of the function with type type. 3 void va_end(va_list ap) This macro allows to end traversal of the variadic function arguments. 4 void va_copy( va_list dest, va_list src ) This macro makes a copy of the variadic function arguments. Print Page Previous Next Advertisements ”;

C Standard Library – Quick Guide ”; Previous Next C Library – <assert.h> The assert.h header file of the C Standard Library provides a macro called assert which can be used to verify assumptions made by the program and print a diagnostic message if this assumption is false. The defined macro assert refers to another macro NDEBUG which is not a part of <assert.h>. If NDEBUG is defined as a macro name in the source file, at the point where <assert.h> is included, the assert macro is defined as follows − #define assert(ignore) ((void)0) Library Macros Following is the only function defined in the header assert.h − Sr.No. Function & Description 1 void assert(int expression) This is actually a macro and not a function, which can be used to add diagnostics in your C program. C Library – <ctype.h> The ctype.h header file of the C Standard Library declares several functions that are useful for testing and mapping characters. All the functions accepts int as a parameter, whose value must be EOF or representable as an unsigned char. All the functions return non-zero (true) if the argument c satisfies the condition described, and zero(false) if not. Library Functions Following are the functions defined in the header ctype.h − Sr.No. Function & Description 1 int isalnum(int c) This function checks whether the passed character is alphanumeric. 2 int isalpha(int c) This function checks whether the passed character is alphabetic. 3 int iscntrl(int c) This function checks whether the passed character is control character. 4 int isdigit(int c) This function checks whether the passed character is decimal digit. 5 int isgraph(int c) This function checks whether the passed character has graphical representation using locale. 6 int islower(int c) This function checks whether the passed character is lowercase letter. 7 int isprint(int c) This function checks whether the passed character is printable. 8 int ispunct(int c) This function checks whether the passed character is a punctuation character. 9 int isspace(int c) This function checks whether the passed character is white-space. 10 int isupper(int c) This function checks whether the passed character is an uppercase letter. 11 int isxdigit(int c) This function checks whether the passed character is a hexadecimal digit. The library also contains two conversion functions that accepts and returns an “int”. Sr.No. Function & Description 1 int tolower(int c) This function converts uppercase letters to lowercase. 2 int toupper(int c) This function converts lowercase letters to uppercase. Character Classes Sr.No. Character Class & Description 1 Digits This is a set of whole numbers { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }. 2 Hexadecimal digits This is the set of { 0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f }. 3 Lowercase letters This is a set of lowercase letters { a b c d e f g h i j k l m n o p q r s t u v w x y z }. 4 Uppercase letters This is a set of uppercase letters {A B C D E F G H I J K L M N O P Q R S T U V W X Y Z }. 5 Letters This is a set of lowercase and uppercase letters. 6 Alphanumeric characters This is a set of Digits, Lowercase letters and Uppercase letters. 7 Punctuation characters This is a set of ! ” # $ % & ” ( ) * + , – . / : ; < = > ? @ [ ] ^ _ ` { | } ~ 8 Graphical characters This is a set of Alphanumeric characters and Punctuation characters. 9 Space characters This is a set of tab, newline, vertical tab, form feed, carriage return, and space. 10 Printable characters This is a set of Alphanumeric characters, Punctuation characters and Space characters. 11 Control characters In ASCII, these characters have octal codes 000 through 037, and 177 (DEL). 12 Blank characters These are spaces and tabs. 13 Alphabetic characters This is a set of Lowercase letters and Uppercase letters. C Library – <errno.h> The errno.h header file of the C Standard Library defines the integer variable errno, which is set by system calls and some library functions in the event of an error to indicate what went wrong. This macro expands to a modifiable lvalue of type int, therefore it can be both read and modified by a program. The errno is set to zero at program startup. Certain functions of the standard C library modify its value to other than zero to signal some types of error. You can also modify its value or reset to zero at your convenience. The errno.h header file also defines a list of macros indicating different error codes, which will expand to integer constant expressions with type int. Library Macros Following are the macros defined in the header errno.h − Sr.No. Macro & Description 1 extern int errno This is the macro set by system calls and some library functions in the event of an error to indicate what went wrong. 2 EDOM Domain Error This macro represents a domain error, which occurs if an input argument is outside the domain, over which the mathematical function is defined and errno is set to EDOM. 3 ERANGE Range Error This macro represents a range error, which occurs if an input argument is outside the range, over which the mathematical function is defined and errno is set to ERANGE. C Library – <float.h> The float.h header file of the C Standard Library contains a set of various platform-dependent constants related to floating point values. These constants are proposed by ANSI C. They allow making more portable programs. Before checking all the constants, it is good to understand that floating-point number is composed of following four elements − Sr.No. Component & Component Description 1 S sign ( +/- ) 2 b base or