学步园

前两天在codeproject挖坟时找到的......

/************************************************************************</p> <p>*char *strcpy(dst, src) - copy one string over another</p> <p>*</p> <p>*Purpose:</p> <p>* Copies the string src into the spot specified by</p> <p>* dest; assumes enough room.</p> <p>*</p> <p>*Entry:</p> <p>* char * dst - string over which "src" is to be copied</p> <p>* const char * src - string to be copied over "dst"</p> <p>*</p> <p>*Exit:</p> <p>* The address of "dst"</p> <p>*</p> <p>*Exceptions:<br /> ************************************************************************/<br /> char* strcpy(char * dst, const char * src)<br /> {<br /> char * cp = dst;<br /> while( *cp++ = *src++ )<br /> ; /* Copy src over dst */<br /> return( dst );<br /> }</p> <p>/************************************************************************</p> <p>*char *strcat(dst, src) - concatenate (append) one string to another</p> <p>*</p> <p>*Purpose:</p> <p>* Concatenates src onto the end of dest. Assumes enough</p> <p>* space in dest.</p> <p>*</p> <p>*Entry:</p> <p>* char *dst - string to which "src" is to be appended</p> <p>* const char *src - string to be appended to the end of "dst"</p> <p>*</p> <p>*Exit:</p> <p>* The address of "dst"</p> <p>*</p> <p>*Exceptions:</p> <p>*<br /> ************************************************************************/<br /> char* strcat ( char * dst , const char * src )<br /> {<br /> char * cp = dst;<br /> while( *cp )<br /> cp++; /* find end of dst */<br /> while( *cp++ = *src++ ) ; /* Copy src to end of dst */<br /> return( dst ); /* return dst */<br /> }</p> <p>/************************************************************************</p> <p>*strcmp - compare two strings, returning less than, equal to, or greater than</p> <p>*</p> <p>*Purpose:</p> <p>* STRCMP compares two strings and returns an integer</p> <p>* to indicate whether the first is less than the second, the two are</p> <p>* equal, or whether the first is greater than the second.</p> <p>*</p> <p>* Comparison is done byte by byte on an UNSIGNED basis, which is to</p> <p>* say that Null (0) is less than any other character (1-255).</p> <p>*</p> <p>*Entry:</p> <p>* const char * src - string for left-hand side of comparison</p> <p>* const char * dst - string for right-hand side of comparison</p> <p>*</p> <p>*Exit:</p> <p>* returns -1 if src < dst</p> <p>* returns 0 if src == dst</p> <p>* returns +1 if src > dst</p> <p>*</p> <p>*Exceptions:</p> <p>*<br /> ************************************************************************/<br /> int strcmp ( const char* src, const char* dst )<br /> {<br /> int ret = 0 ;<br /> while( !(ret = *(unsigned char *)src - *(unsigned char *)dst) && *dst)<br /> ++src, ++dst;<br /> if ( ret < 0 )<br /> ret = -1 ;<br /> else if ( ret > 0 )<br /> ret = 1 ;<br /> return( ret );<br /> }