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std::memchr(3) C++ Standard Libary std::memchr(3)


std::memchr - std::memchr


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

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.


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.

// Run this code

#include <iostream>
#include <cstring>

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

strchr finds the first occurrence of a character
find_if finds the first element satisfying specific criteria
find_if_not (function template)