strstr.c

来自「test file nucleus source」· C语言 代码 · 共 89 行

/*************************************************************************
*
*               Copyright Mentor Graphics Corporation 2002
*                         All Rights Reserved.
*
* THIS WORK CONTAINS TRADE SECRET AND PROPRIETARY INFORMATION WHICH IS
* THE PROPERTY OF MENTOR GRAPHICS CORPORATION OR ITS LICENSORS AND IS
* SUBJECT TO LICENSE TERMS.
*
*************************************************************************/

/*************************************************************************
* FILE NAME                                     VERSION
*
*       strstr.c                                Nucleus Common Library 1.1
*
* DESCRIPTION
*
*       This file contains the implementation of NCL_strstr.
*
* DATA STRUCTURES
*
*       None.
*
* FUNCTIONS
*
*       NCL_strstr
*
* DEPENDENCIES
*
*       ncl.h
*       string.h
*       nucleus.h
*
************************************************************************/

#define NU_NCL_SOURCE_FILE

#include "ncl\inc\ncl.h"
#include "ncl\inc\string.h"
#include "plus\nucleus.h"                                /* MMU Support */

/*************************************************************************
*
*   FUNCTION
*
*       NCL_strstr
*
*   DESCRIPTION
*
*       Return a pointer to first occurrence within string
*       s1 of string s2, or return zero if s1 does not
*       contain any instance of s2.  If *s2 == 0, return s1.
*
*   INPUTS
*
*       s1                  String to search within
*       s2                  String to search for
*
*   OUTPUTS
*
*       char*               Pointer to first occurance of s1 in s2 or 0 if
*                             s1 does not contain any instance of s2.
*
*************************************************************************/

char *NCL_strstr(register const char *s1, register const char *s2)
{
    register size_t len2;

    len2 = NCL_strlen(s2);

    if (!len2)
    {
        return (char *)s1;
    }

    for (; *s1; ++s1)
    {
        if (*s1 == *s2 && NCL_strncmp(s1, s2, len2)==0)
        {
            return (char *)s1;
        }
    }

    return 0;
}