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

1.1       root        1: #include "../h/rt.h"
                      2: 
                      3: /*
                      4:  * -x - negate x.
                      5:  */
                      6: 
                      7: neg(nargs, arg1, arg0)
                      8: int nargs;
                      9: struct descrip arg1, arg0;
                     10:    {
                     11:    DclSave
                     12:    union numeric n;
                     13:    long l;
                     14: 
                     15:    SetBound;
                     16:    /*
                     17:     * x must be numeric.
                     18:     */
                     19:    switch (cvnum(&arg1, &n)) {
                     20:       case T_LONGINT:
                     21:          /*
                     22:           * If it's an integer, check for overflow by negating it and
                     23:           *  seeing if the negation didn't "work".  Use mkint to
                     24:           *  construct the return value.
                     25:           */
                     26:          l = -n.integer;
                     27:          if (n.integer < 0 && l < 0)
                     28:             runerr(203, &arg1);
                     29:          mkint(l, &arg0);
                     30:          break;
                     31: 
                     32:       case T_REAL:
                     33:          /*
                     34:           * x is real, just negate it and use mkreal to construct the
                     35:           *  return value.
                     36:           */
                     37:          mkreal(-n.real, &arg0);
                     38:          break;
                     39: 
                     40:       default:
                     41:          /*
                     42:           * x isn't numeric.
                     43:           */
                     44:          runerr(102, &arg1);
                     45:       }
                     46:    ClearBound;
                     47:    }
                     48: 
                     49: Opblock(neg,1,"-")

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