strcpy，strcat和strcmp的實現原始碼

char* strcpy(char * dst, const char * src)

{

char * cp = dst;

while( *cp++ = *src++ ); /* Copy src over dst */

return( dst );

}

Char* strcat ( char * dst , const char * src )

{

char * cp = dst;

while( *cp )

cp++; /* find end of dst */

while( *cp++ = *src++ ) ; /* Copy src to end of dst */

return( dst ); /* return dst */

}

/* returns -1 if src < dst

* returns 0 if src == dst

* returns +1 if src > dst

*/

int strcmp ( const char* src, const char* dst )

{

int ret = 0 ;

while( ! (ret = *(unsigned char *)src - *(unsigned char *)dst) && *dst)

++src, ++dst;

if ( ret < 0 )

ret = -1 ;

else if ( ret > 0 )

ret = 1 ;

return( ret );

}