std::memchr(3)

💖 std::memchr 💖

okay so bestie, this is the std::memchr page from the C++ Standard Libary — manual name folded in near the top, we're not copying header lines today. It's giving standard-library finder energy, and yes, the whole NAME section is literally just the same thing twice — iconic.

✨ NAME ✨

std::memchr — std::memchr (that's the name, no extra notes, periodt).

🦋 Synopsis 🦋

Defined in header <cstring>:

const void* memchr( const void* ptr, int ch, std::size_t count );
void* memchr(       void* ptr, int ch, std::size_t count );

okay so here's the actual behavior, and it's lowkey specific: it converts ch to unsigned char and locates the first occurrence of that value in the initial count bytes — each of those bytes is interpreted as unsigned char — of the object pointed to by ptr.

This function behaves as if it reads the bytes sequentially and stops as soon as a matching bytes is found: if the array pointed to by ptr (since C++17) is smaller than count, but the match is found within the array, the behavior is well-defined.

yes, that (since C++17) is doing important work, bestie — don't lose it.

🎀 Parameters 🎀

• ptr — pointer to the object to be examined
• ch — byte to search for
• count — max number of bytes to examine

💖 Return value 💖

Pointer to the location of the byte, or a null pointer if no such byte is found.

🌸 Example 🌸

Search an array of characters. Run this code:

// Run this code

#include <cstring>
#include <iostream>

int main()
{
    char arr[] = {'a', '\0', 'a', 'A', 'a', 'a', 'A', 'a'};
    char *pc = (char*) std::memchr(arr, 'A', sizeof arr);
    if (pc != nullptr)
        std::cout << "search character found\n";
    else
        std::cout << "search character not found\n";
}

🌈 Output 🌈

search character found

👑 See also 👑

• strchr — finds the first occurrence of a character (function)
• find
• find_if — finds the first element satisfying specific criteria
• find_if_not (function template)
• (C++11)
• C documentation for memchr

kisses and byeee: this page came from http://cppreference.com, version/date 2024.06.10, and the footer says std::memchr(3). mwah 💅💖