std::strlen(3)

🎀 NAME 🎀

okay bestie, welcome to the std::strlen(3) page from the C++ Standard Libary manual 💅. The name is literally std::strlen - std::strlen (yes, that's the whole NAME section, no cap). We're gonna get you comfy with it.

✨ Synopsis ✨

Defined in header <cstring>:

std::size_t strlen( const char* str );

So std::strlen returns the length of the given byte string — that's the number of characters in a character array whose first element is pointed to by str, up to and not including the first null character 🫶. The behavior is undefined if there is no null character in the character array pointed to by str 😭. Like, fr fr, do not let that happen.

🌸 Parameters 🌸

• str — pointer to the null-terminated byte string to be examined 🔍

💖 Return value 💖

The length of the null-terminated string str ✨.

🦋 Possible implementation 🦋

Here's the possible implementation, bestie — copy the shape, not my whole personality:

std::size_t strlen(const char* start)
{
    // NB: start is not checked for nullptr!
    const char* end = start;
    while (*end != '\0')
        ++end;
    return end - start;
}

🍓 Example 🍓

// Run this code

#include <cstring>
#include <iostream>

int main()
{
    const char str[] = "dog cat\0mouse";

    std::cout << "without null character: " << std::strlen(str) << '\n'
              << "with null character: " << sizeof str << '\n';
}

💻 Output:

without null character: 7
with null character: 14

👑 See also 👑

• wcslen — returns the length of a wide string (function) 🌈
• mblen — returns the number of bytes in the next multibyte character (function) 🧚
• C documentation for strlen 📚

Source: http://cppreference.com · version/date: 2024.06.10 · page: std::strlen(3) 💜