Source code: Implementation source code of Microsoft strcpy, strcat and strcmp

 

/***

* Char * strcpy (DST, Src)-copy one string over another

*

* Purpose:

* Copies the string SRC into the spot specified

* DEST; assumes enough room.

*

* Entry:

* Char * DST-string over which "src" is to be copied

* Const char * Src-string to be copied over "DST"

*

* Exit:

* The address of "DST"

*

* Exceptions:

**************************************** ***************************************/

Char * strcpy (char * DST, const char * SRC)

{

Char * CP = DST;

While (* CP ++ = * SRC ++)

;/* Copy SRC over DST */

Return (DST );

}

/***

* Char * strcat (DST, Src)-concatenate (append) one string to another

*

* Purpose:

* Concatenates SRC onto the end of DeST. Assumes enough

* Space in DeST.

*

* Entry:

* Char * DST-string to which "src" is to be appended

* Const char * Src-string to be appended to the end of "DST"

*

* Exit:

* The address of "DST"

*

* Exceptions:

*

**************************************** ***************************************/

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 */

}

/***

* Strcmp-compare two strings, returning less than, equal to, or greater

*

* 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

* 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 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 );

}