Character vs string comparison in C++

Introduction

We compare characters and strings to check if they are the same or different. Characters are single letters, while strings are groups of letters.

Checking if a typed letter matches a specific character, like 'y' or 'n'.

Comparing user input to a word, like checking if input is "yes" or "no".

Validating a single character in a password or code.

Deciding actions based on a single letter or a whole word.

Syntax

C++

char c = 'a';
std::string s = "a";

// Compare character to character
if (c == 'a') {
    // do something
}

// Compare string to string
if (s == "a") {
    // do something
}

// Comparing char to string directly is not allowed
// if (c == s) { // error }

// To compare char and string, convert char to string first
if (std::string(1, c) == s) {
    // do something
}

Characters use single quotes: 'a'. Strings use double quotes: "a".

You cannot compare a char and a string directly in C++ without conversion.

Examples

Compare a character variable to a character literal.

C++

char c = 'x';
if (c == 'x') {
    // true
}

Compare a string variable to a string literal.

C++

std::string s = "hello";
if (s == "hello") {
    // true
}

Convert char to string to compare with a string.

C++

char c = 'a';
std::string s = "a";
if (std::string(1, c) == s) {
    // true
}

Sample Program

This program shows how to compare a character to a character literal, a string to a string literal, and how to compare a character to a string by converting the character to a string first.

C++

#include <iostream>
#include <string>

int main() {
    char c = 'g';
    std::string s = "g";

    if (c == 'g') {
        std::cout << "Character matches 'g'\n";
    }

    if (s == "g") {
        std::cout << "String matches \"g\"" << std::endl;
    }

    // Direct comparison (char == string) is not allowed
    // So convert char to string first
    if (std::string(1, c) == s) {
        std::cout << "Char and string are equal after conversion" << std::endl;
    }

    return 0;
}

Important Notes

Remember to use single quotes for characters and double quotes for strings.

Trying to compare a char and a string directly will cause a compile error in C++.

Use std::string(1, c) to convert a char to a string of length 1.

Summary

Characters and strings are different types in C++.

You can compare characters to characters and strings to strings directly.

To compare a character with a string, convert the character to a string first.