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String.md

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String functions

gets(str) : Get string from stdin(with End Marker in cell #0), save the input string(starts from cell #0) and move the pointer to the end(new position the of End Marker)

/**
 *  INPUT:  char *buffer
 *  CODES:
 *          char *p0 = buffer;
 *          char *p1 = NEXT_TO p0;
 *          char *p2 = NEXT_TO p1;
 *          while (*p0) {
 *              *p2 = *p1 = *p0;            // move EOT forward
 *              *p0 = getch();
 *              if (*p0 NOT_EQUALS *p1) {   // the input char is not EOT
 *                  RESTORE INPUT VALUE TO *p0;
 *                  MOVE ALL POINTERS FORWARD;
 *                  *p0 = EOT;
 *                  *p1 = *p2 = 0;
 *              } else {
 *                  *p0 = *p1 = 0;
 *                  *p2 = EOT;
 *              }
 *          }
 *          *p0 = *p2;                      // EOT
 */

                    // 13*                              set the End Marker(EOT) in the cell #0

>[-]<               // 13*  (0)                         clear cell #1
[
    >>[-]<<         // 13*   0   (0) | 49  13*  0  (0)  clear cell #2
    [->+>+<<]       //  0*  13   13  | 49   0* 13  13   move EOT forward
    ,               // 49*  13   13  | 49  13* 13  13   get char from stdin
    [->-<]          //  0* ~36   13  | 49   0*  0  13   check difference with EOT
    >[              //  0  ~36*  13  | 49   0   0* 13   if (char <> EOT)
        [+<+>]      // 36    0*  13                         move the difference back
        >           // 36    0   13*                        (DO NOT reset the pointer for next round)
        [-<+<+>>]   // 49   13    0*                        restore the input char
    ]<              // 49   13*   0  | 49   0*  0  13   move the pointer back to cell #0(next round)
]
>>[-<<+>>]<<        //               | 49  13*  0   0   move the EOT back

getstring(str) : Get string from stdin, save the input string starts from cell #1 and retore the pointer to #0

/**
 *  INPUT:  char *buffer
 *  CODES:
 *          char *p0 = buffer;
 *          char *p1 = NEXT_TO p0;
 *          *p0 = 0;
 *          *p1 = 13;   // EOT
 *          gets(p1);   // store the input string from cell #1
 *          KEEP the pointer pointing to p0(buffer);
 */

[-]>                // clear cell #0
[-]+++++ +++++ +++  // set the End Marker(EOT) in the cell #1
gets(str)
[<]                 // back to cell #0