Double is a standard data type in Swift. Double data type is used to store decimal numbers like 23.344, 45.223221, 0.324343454, etc. It is a 64-bit floating-point number and stores values up to 15 decimal digits which makes it more accurate as compared to Float.

If you create a variable to store a decimal number without specifying its type, then by default compiler will assume it is a Double type instead of a Float type, due to high precision.

Syntax

Following is the syntax of the Double data type −

let num : Double = 23.4554

Following is the shorthand syntax of the Double data type −

let num = 2.73937

Example

Swift program to calculate the sum of two double numbers.

import Foundation

// Defining double numbers
let num1 : Double = 2.3764
let num2 : Double = 12.738

// Store the sum of two double numbers
var sum : Double = 0.0
sum = num1 + num2
print("Sum of (num1) and (num2) = (sum)")

Output

Sum of 2.3764 and 12.738 = 15.1144

Example

Swift program to calculate the product of two double numbers.

import Foundation

// Defining double numbers
let num1 = 12.3764832
let num2 = 22.7388787779074

// Store the product of two double numbers
var product = 0.0
product = num1 * num2
print("Product of (num1) and (num2) = (product)")

Output

Product of 12.3764832 and 22.7388787779074 = 281.42735118160743

Difference Between Float and Double

The following are the major differences between the floating point data type and the double data type.