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 );

Converts ch to unsigned char and locates the first occurrence of that value in the initial count bytes (each 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 is smaller than count, but the match is found within the array, the behavior is well-defined.

(since C++17)


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.


Search an array of characters.

#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";
        std::cout << "search character not found\n";


search character found

See also

finds the first occurrence of a character
finds the first element satisfying specific criteria
(function template)
C documentation for memchr

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