C++ || How To Check If A String Starts & Ends With A Certain String Using C++

December 09, 2020 admin No comments

The following is a module with functions which demonstrates how to determine if a string starts and ends with a certain substring using C++.

1. Starts With

The example below demonstrates the use of ‘Utils::startsWith‘ to determine whether the beginning of a string instance matches a specified string value.





		
		
			1. Starts With
			
C++
			
			// Starts With

// Declare values
std::string values[] = { "This is a string.", "Hello!",
                          "Nothing.", "Yes.", "randomize" };
// Declare search
std::string search = "Th";

// Check if items starts with search value
for (const auto& value : values) {
    std::cout << "'" << value << "' starts with '" << search << "': " 
        << (Utils::startsWith(value, search) ? "True" : "False") << std::endl;
}

// example output:
/*
    'This is a string.' starts with 'Th': True
    'Hello!' starts with 'Th': False
    'Nothing.' starts with 'Th': False
    'Yes.' starts with 'Th': False
    'randomize' starts with 'Th': False
*/
			
				
					
				
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						// Starts With
 
// Declare values
std::string values[] = { "This is a string.", "Hello!",
                          "Nothing.", "Yes.", "randomize" };
// Declare search
std::string search = "Th";
 
// Check if items starts with search value
for (const auto& value : values) {
    std::cout << "'" << value << "' starts with '" << search << "': " 
        << (Utils::startsWith(value, search) ? "True" : "False") << std::endl;
}
 
// example output:
/*
    'This is a string.' starts with 'Th': True
    'Hello!' starts with 'Th': False
    'Nothing.' starts with 'Th': False
    'Yes.' starts with 'Th': False
    'randomize' starts with 'Th': False
*/

2. Ends With

The example below demonstrates the use of ‘Utils::endsWith‘ to determine whether the end of a string instance matches a specified string value.





		
		
			2. Ends With
			
C++
			
			// Ends With

// Declare values
std::string values[] = { "This is a string.", "Hello!",
                          "Nothing.", "Yes.", "randomize" };
// Declare search
std::string search = ".";

// Check if items ends with search value
for (const auto& value : values) {
    std::cout << "'" << value << "' ends with '" << search << "': "
        << (Utils::endsWith(value, search) ? "True" : "False") << std::endl;
}

// example output:
/*
    'This is a string.' ends with '.': True
    'Hello!' ends with '.': False
    'Nothing.' ends with '.': True
    'Yes.' ends with '.': True
    'randomize' ends with '.': False
*/
			
				
					
				
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						// Ends With
 
// Declare values
std::string values[] = { "This is a string.", "Hello!",
                          "Nothing.", "Yes.", "randomize" };
// Declare search
std::string search = ".";
 
// Check if items ends with search value
for (const auto& value : values) {
    std::cout << "'" << value << "' ends with '" << search << "': "
        << (Utils::endsWith(value, search) ? "True" : "False") << std::endl;
}
 
// example output:
/*
    'This is a string.' ends with '.': True
    'Hello!' ends with '.': False
    'Nothing.' ends with '.': True
    'Yes.' ends with '.': True
    'randomize' ends with '.': False
*/

3. Utils Namespace

The following is the Utils Namespace. Include this in your project to start using!





		
		
			Utils Namespace
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Dec 9, 2020
//    Taken From: http://programmingnotes.org/
//    File:  Utils.h
//    Description: Handles general utility functions
// ============================================================================
#pragma once
#include <string>

namespace Utils {
    /**
    * FUNCTION: startsWith 
    * USE: Determines whether the beginning of a string instance matches 
    *   a specified string value
    * @param source: The source string
    * @param value: The string to compare
    * @return: True if 'value' matches the beginning of 'source', 
    *   False otherwise
    */
    bool startsWith(const std::string& source, const std::string& value) {
        return source.size() >= value.size() 
            && source.compare(0, value.size(), value) == 0;
    }

    /**
    * FUNCTION: endsWith 
    * USE: Determines whether the end of a string instance matches
    *   a specified string value
    * @param source: The source string
    * @param value: The string to compare to the substring at the end
    * @return: True if 'value' matches the end of 'source',
    *   False otherwise
    */
    bool endsWith(const std::string& source, const std::string& value) {
        return source.size() >= value.size()
            && source.compare(source.size() - value.size(), value.size(), value) == 0;
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Dec 9, 2020
//    Taken From: http://programmingnotes.org/
//    File:  Utils.h
//    Description: Handles general utility functions
// ============================================================================
#pragma once
#include <string>
 
namespace Utils {
    /**
    * FUNCTION: startsWith 
    * USE: Determines whether the beginning of a string instance matches 
    *   a specified string value
    * @param source: The source string
    * @param value: The string to compare
    * @return: True if 'value' matches the beginning of 'source', 
    *   False otherwise
    */
    bool startsWith(const std::string& source, const std::string& value) {
        return source.size() >= value.size() 
            && source.compare(0, value.size(), value) == 0;
    }
 
    /**
    * FUNCTION: endsWith 
    * USE: Determines whether the end of a string instance matches
    *   a specified string value
    * @param source: The source string
    * @param value: The string to compare to the substring at the end
    * @return: True if 'value' matches the end of 'source',
    *   False otherwise
    */
    bool endsWith(const std::string& source, const std::string& value) {
        return source.size() >= value.size()
            && source.compare(source.size() - value.size(), value.size(), value) == 0;
    }
}// http://programmingnotes.org/

4. More Examples

Below are more examples demonstrating the use of the ‘Utils‘ Namespace. Don’t forget to include the module when running the examples!





		
		
			More Examples
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Dec 9, 2020
//    Taken From: http://programmingnotes.org/
//    File:  program.cpp
//    Description: The following demonstrates the use of the Utils Namespace
// ============================================================================
#include <iostream>
#include <string>
#include <exception>
#include "Utils.h"

void display(const std::string& message);

int main() {
    try {
        // Declare values
        std::string values[] = { "This is a string.", "Hello!",
                                  "Nothing.", "Yes.", "randomize" };

        // Declare search
        std::string search = "Th";

        // Check if items starts with search value
        for (const auto& value : values) {
            std::cout << "'" << value << "' starts with '" << search << "': " 
                << (Utils::startsWith(value, search) ? "True" : "False") << std::endl;
        }

        display("");


        // Declare values
        std::string values2[] = { "This is a string.", "Hello!",
                                  "Nothing.", "Yes.", "randomize" };

        // Declare search
        std::string search2 = ".";

        // Check if items ends with search value
        for (const auto& value : values2) {
            std::cout << "'" << value << "' ends with '" << search2 << "': "
                << (Utils::endsWith(value, search2) ? "True" : "False") << std::endl;
        }
    } catch (std::exception& e) {
        display("\nAn error occurred: " + std::string(e.what()));
    }

    std::cin.get();
    return 0;
}

void display(const std::string& message) {
    std::cout << message << std::endl;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Dec 9, 2020
//    Taken From: http://programmingnotes.org/
//    File:  program.cpp
//    Description: The following demonstrates the use of the Utils Namespace
// ============================================================================
#include <iostream>
#include <string>
#include <exception>
#include "Utils.h"
 
void display(const std::string& message);
 
int main() {
    try {
        // Declare values
        std::string values[] = { "This is a string.", "Hello!",
                                  "Nothing.", "Yes.", "randomize" };
 
        // Declare search
        std::string search = "Th";
 
        // Check if items starts with search value
        for (const auto& value : values) {
            std::cout << "'" << value << "' starts with '" << search << "': " 
                << (Utils::startsWith(value, search) ? "True" : "False") << std::endl;
        }
 
        display("");
 
 
        // Declare values
        std::string values2[] = { "This is a string.", "Hello!",
                                  "Nothing.", "Yes.", "randomize" };
 
        // Declare search
        std::string search2 = ".";
 
        // Check if items ends with search value
        for (const auto& value : values2) {
            std::cout << "'" << value << "' ends with '" << search2 << "': "
                << (Utils::endsWith(value, search2) ? "True" : "False") << std::endl;
        }
    } catch (std::exception& e) {
        display("\nAn error occurred: " + std::string(e.what()));
    }
 
    std::cin.get();
    return 0;
}
 
void display(const std::string& message) {
    std::cout << message << std::endl;
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

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Posted in: Basic, C++ Tags: c++, string

C++ || How To Check If A String Starts & Ends With A Certain String Using C++

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