Custom character literals in C++

23 Oct 2023

programming

In C++, character literals are a convenient way to represent individual characters. However, the standard character literals are limited to a predefined set of characters, such as ‘a’, ‘b’, ‘0’, etc. But what if you want to define your own custom character literals?

Fortunately, C++ provides a mechanism to define custom character literals using user-defined literals (UDLs). UDLs allow you to extend the set of character literals with your own custom representations. This can be useful in scenarios where you want to define special characters or symbols specific to your application or domain.

Defining Custom Character Literals

To define a custom character literal, you need to write a user-defined literal operator function. This function is responsible for interpreting the literal and returning the desired character value.

char operator"" _custom(char c)
{
    // custom interpretation of the character literal
    // return the desired character value
    if (c == 'c') {
        return '%';  // for example, interpret 'c' as '%'
    }
    
    // handle other custom cases
    
    return c;  // default behavior, return the original character
}

In the above example, the _custom literal operator function is defined. It takes a single char parameter and returns a char. Inside the function, you can implement your own logic to interpret the character literal.

Using Custom Character Literals

Once you have defined your custom character literals, you can use them just like the standard character literals. Here’s an example:

char myChar = 'c'_custom;  // using the custom character literal 'c'
// myChar will be assigned the value '%'

In the above code snippet, the custom character literal ‘c’ is used and converted to the desired character value ‘%’. The result is then assigned to the variable myChar.

Conclusion

Custom character literals in C++ allow you to define your own interpretations of character literals beyond the standard set. By using user-defined literals, you can extend the built-in capabilities of the language and make your code more expressive and tailored to your application’s needs.

With this feature, you can create custom character literals that represent special characters or symbols specific to your domain or application. This can enhance the readability and maintainability of your code.

So the next time you find yourself needing to represent a custom character literal in C++, remember that you have this powerful feature at your disposal.

References:

#cpp #programming