Swift - Double



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.

Double Float
It has precision of at least 15 decimal digits. It has precision of at least 6 decimal digits.
Memory size is of 8 bytes. Memory size is of 4 bytes.
If no data type is defined, then compiler will treat it as Double. It is not preferred by the compiler by default.
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