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Euphoria – Constants ”; Previous Next Constants are also variables that are assigned an initial value that can never change in the program’s life. Euphoria allows to define constants using constant keyword as follows − constant MAX = 100 constant Upper = MAX – 10, Lower = 5 constant name_list = {“Fred”, “George”, “Larry”} The result of any expression can be assigned to a constant, even one involving calls to previously defined functions, but once the assignment is made, the value of the constant variable is “locked in”. Constants may not be declared inside a subroutine. The scope of a constant that does not have a scope modifier, starts at the declaration and ends and the end of the file it is declared in. Examples #!/home/euphoria-4.0b2/bin/eui constant MAX = 100 constant Upper = MAX – 10, Lower = 5 printf(1, “Value of MAX %dn”, MAX ) printf(1, “Value of Upper %dn”, Upper ) printf(1, “Value of Lower %dn”, Lower ) MAX = MAX + 1 printf(1, “Value of MAX %dn”, MAX ) This produces the following error − ./test.ex:10 <0110>:: may not change the value of a constant MAX = MAX + 1 ^ Press Enter If you delete last two lines from the example, then it produces the following result − Value of MAX 100 Value of Upper 90 Value of Lower 5 The enums An enumerated value is a special type of constant where the first value defaults to the number 1 and each item after that is incremented by 1. Enums can only take numeric values. Enums may not be declared inside a subroutine. The scope of an enum that does not have a scope modifier, starts at the declaration and ends and the end of the file it is declared in. Examples #!/home/euphoria-4.0b2/bin/eui enum ONE, TWO, THREE, FOUR printf(1, “Value of ONE %dn”, ONE ) printf(1, “Value of TWO %dn”, TWO ) printf(1, “Value of THREE %dn”, THREE ) printf(1, “Value of FOUR %dn”, FOUR ) This will produce following result − Value of ONE 1 Value of TWO 2 Value of THREE 3 Value of FOUR 4 You can change the value of any one item by assigning it a numeric value. Subsequent values are always the previous value plus one, unless they too are assigned a default value. #!/home/euphoria-4.0b2/bin/eui enum ONE, TWO, THREE, ABC=10, XYZ printf(1, “Value of ONE %dn”, ONE ) printf(1, “Value of TWO %dn”, TWO ) printf(1, “Value of THREE %dn”, THREE ) printf(1, “Value of ABC %dn”, ABC ) printf(1, “Value of XYZ %dn”, XYZ ) This produce the following result − Value of ONE 1 Value of TWO 2 Value of THREE 3 Value of ABC 10 Value of XYZ 11 Sequences use integer indices, but with enum you may write code like this − enum X, Y sequence point = { 0,0 } point[X] = 3 point[Y] = 4 Print Page Previous Next Advertisements ”;