strcmp.c

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/***
*strcmp.c - routine to compare two strings (for equal, less, or greater)
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       Compares two string, determining their ordinal order.
*
*******************************************************************************/
 
#include <string.h>
 
#pragma function(strcmp)
 
/***
*strcmp - compare two strings, returning less than, equal to, or greater than
*
*Purpose:
*       STRCMP compares two strings and returns an integer
*       to indicate whether the first is less than the second, the two are
*       equal, or whether the first is greater than the second.
*
*       Comparison is done byte by byte on an UNSIGNED basis, which is to
*       say that Null (0) is less than any other character (1-255).
*
*Entry:
*       const char * src - string for left-hand side of comparison
*       const char * dst - string for right-hand side of comparison
*
*Exit:
*       returns -1 if src <  dst
*       returns  0 if src == dst
*       returns +1 if src >  dst
*
*Exceptions:
*
*******************************************************************************/
 
int __cdecl strcmp (
        const char * src,
        const char * dst
        )
{
        int ret = 0 ;
 
        while((ret = *(unsigned char *)src - *(unsigned char *)dst) == 0 && *dst)
                {
                ++src, ++dst;
                }
 
        return ((-ret) < 0) - (ret < 0); // (if positive) - (if negative) generates branchless code
}