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Annotation of 43BSD/contrib/icon/operators/cat.c, revision 1.1.1.1

1.1       root        1: #include "../h/rt.h"
                      2: 
                      3: /*
                      4:  * x || y - concatenate strings x and y.
                      5:  */
                      6: 
                      7: cat(nargs, arg2, arg1, arg0)
                      8: int nargs;
                      9: struct descrip arg2, arg1, arg0;
                     10:    {
                     11:    DclSave
                     12:    char sbuf1[MAXSTRING], sbuf2[MAXSTRING];
                     13:    extern char *alcstr();
                     14: 
                     15:    SetBound;
                     16:    /*
                     17:     * x and y must be strings.
                     18:     */
                     19:    if (cvstr(&arg1, sbuf1) == NULL)
                     20:       runerr(103, &arg1);
                     21:    if (cvstr(&arg2, sbuf2) == NULL)
                     22:       runerr(103, &arg2);
                     23: 
                     24:    /*
                     25:     * Ensure space for the resulting string.
                     26:     */
                     27:    sneed(STRLEN(arg1)+STRLEN(arg2));
                     28:    if (STRLOC(arg1) + STRLEN(arg1) == sfree)
                     29:       /*
                     30:        * The end of x is at the end of the string space, hence, x was the
                     31:        *  last string allocated.  x is not recopied, rather, y is appended
                     32:        *  to the string space and the result is pointed at the start of x.
                     33:        */
                     34:       STRLOC(arg0) = STRLOC(arg1);
                     35:    else
                     36:       /*
                     37:        * Append x to the end of the string space and point the result
                     38:        *  at the start of x.
                     39:        */
                     40:       STRLOC(arg0) = alcstr(STRLOC(arg1),STRLEN(arg1));
                     41:    /*
                     42:     * Append y to the end of the string space.
                     43:     */
                     44:    alcstr(STRLOC(arg2),STRLEN(arg2));
                     45:    /*
                     46:     *  Set the length of the result and return.
                     47:     */
                     48:    STRLEN(arg0) = STRLEN(arg1) + STRLEN(arg2);
                     49:    ClearBound;
                     50:    }
                     51: 
                     52: Opblock(cat,2,"||")

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