Swift String hasPrefix() Function

String hasPrefix() Function

The hasPrefix() method of String structure is used to determine whether the given string begins with the specified string or not. This method is case-sensitive means S and s are different.

For example, we have a string Tutorials Point, now using hasPrefix(Tut) method we can check whether the given string starts with Tut or not. Here this method returns true because the given string starts with Tut.

Syntax

Following is the syntax of the hasPrefix() method −

func hasPrefix(_prefixStr: String)-> Bool

Parameters

This function takes only one parameter which is prefixStr. It represents a prefix string.

Return Value

This method returns a boolean value. If the given string starts with the specified string, then this method will return true. Otherwise, this method will return false.

Example 1

Swift program to demonstrate how to use the hasPrefix() method −

import Foundation

// Declaring a string
var str = "Mohit likes Swift and C++"
let prefixStr1 = "Mo"
let prefixStr2 = "Is"

// Checking whether the given string starts with the specified prefix string or not.
// Using hasPrefix() method
print("Is '\(str)' starts with '\(prefixStr1)'?:", str.hasPrefix(prefixStr1))
print("Is '\(str)' starts with '\(prefixStr2)'?:", str.hasPrefix(prefixStr2))

Output

Is 'Mohit likes Swift and C++' starts with 'Mo'?: true
Is 'Mohit likes Swift and C++' starts with 'Is'?: false

Example 2

Swift program to check the prefix string −

import Foundation

// String
var str = "My car color is blue"
 
// Using hasPrefix() method
print(str.hasPrefix("My"))
print(str.hasPrefix("M"))
print(str.hasPrefix("The"))
print(str.hasPrefix("Hello"))

Output

true
true
false
false

Example 3

Swift program to check whether the string starts with the given string or not −

import Foundation

// String
var str = "Mohan is going to market"

// Checking whether the given string starts with the specified prefix string or not.
// Using hasPrefix() method
if (str.hasPrefix("Mohan")){
   print("Yes! The given string starts with the prefix 'Mohan'")
}else{
   print("No! The given string does not starts with the prefix 'Mohan'")
}

Output

Yes! The given string starts with the prefix 'Mohan'