strstr查找字符串, strch查找字符 (在字符串中) [Microsoft Corporation]

/***
*char *strchr(string, c) - search a string for a character
*
*Purpose:
*       Searches a string for a given character, which may be the
*       null character '\0'.
*
*Entry:
*       char *string - string to search in
*       char c - character to search for
*
*Exit:
*       returns pointer to the first occurence of c in string
*       returns NULL if c does not occur in string
*
*Exceptions:
*
*******************************************************************************/

char * __cdecl strchr (
        const char * string,
        int ch
        )
{
        while (*string && *string != (char)ch)
                string++;

        if (*string == (char)ch)
                return((char *)string);
        return(NULL);
}





/***
*char *strstr(string1, string2) - search for string2 in string1
*
*Purpose:
*       finds the first occurrence of string2 in string1
*
*Entry:
*       char *string1 - string to search in
*       char *string2 - string to search for
*
*Exit:
*       returns a pointer to the first occurrence of string2 in
*       string1, or NULL if string2 does not occur in string1
*
*Uses:
*
*Exceptions:
*
*******************************************************************************/

char * __cdecl strstr (
        const char * str1,
        const char * str2
        )
{
        char *cp = (char *) str1;
        char *s1, *s2;

        if ( !*str2 )
            return((char *)str1);

        while (*cp)
        {
                s1 = cp;
                s2 = (char *) str2;

                while ( *s1 && *s2 && !(*s1-*s2) )
                        s1++, s2++;

                if (!*s2)
                        return(cp);

                cp++;
        }

        return(NULL);

}