std:: memchr

From cppreference.com
C++
Strings library
Null-terminated byte strings
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)

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 
#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

finds the first occurrence of a character
(function)
(C++11)
finds the first element satisfying specific criteria
(function template)
C documentation for memchr
Retrieved from " https://en.cppreference.com/mwiki/index.php?title=cpp/string/byte/memchr&oldid=152823 "