How to check if a string starts with another string in C?

Question

Is there something like startsWith(str_a, str_b) in the standard C library?

It should take pointers to two strings that end with nullbytes, and tell me

Answer 1

Or a combination of the two approaches:

_Bool starts_with(const char *restrict string, const char *restrict prefix)
{
    char * const restrict prefix_end = prefix + 13;
    while (1)
    {
        if ( 0 == *prefix  )
            return 1;   
        if ( *prefix++ != *string++)
            return 0;
        if ( prefix_end <= prefix  )
            return 0 == strncmp(prefix, string, strlen(prefix));
    }  
}

EDIT: The code below does NOT work because if strncmp returns 0 it is not known if a terminating 0 or the length (block_size) was reached.

An additional idea is to compare block-wise. If the block is not equal compare that block with the original function:

_Bool starts_with_big(const char *restrict string, const char *restrict prefix)
{
    size_t block_size = 64;
    while (1)
    {
        if ( 0 != strncmp( string, prefix, block_size ) )
          return starts_with( string, prefix);
        string += block_size;
        prefix += block_size;
        if ( block_size < 4096 )
          block_size *= 2;
    }
}

The constants 13, 64, 4096, as well as the exponentiation of the block_size are just guesses. It would have to be selected for the used input data and hardware.