/***********************  07-2-S.TXT  **************************
 ***********  Prof. Dr. B. Bartning  ***************************/

// Hints for solutions of 07-2.CPP

(b) Removing function declaration not allowed.
    After reordering the text (definition of "rationalCalc"
    before "main"): permitted.

(c) Altering the declaration only:
    Compiler: warnings (variables k,l,m,n used before initializing)
    Linker: error (unresolved name: function "rationalCalc" with six
            int's not found)

    After altering the definition, too:
    Compiler warnings just as above.
    No linker error.
    Not sensible because calculation results (from "rationalCalc")
    are not available in the main program.

(d) Altering reference into constant reference: not permitted because
    parameters are changed in the function.

    Altering value parameter into reference: permitted.
    But a call of "rationalCalc(i+j,...)" is not permitted.

    Altering into constant references: possible.
    Now the call "rationalCalc(i+j,...)" is allowed, too.

(e) Function definition (declaration: do it yourself!)
      bool safeDivMult(double val1, double val2, double &quotient, double &product)
      {
         // multiplication permitted, anyway:
         product = val1*val2;

         // division not permitted if denominator (val2) equals zero:
         if (val2==0.0) {
            quotient = 0.0; // not correct, but a definite value
            return false;
         }
         // the following: possible also as "else" branch of the "if" above
         quotient = val1/val2;
         return true;
      }

(f) Function definition (declaration: do it yourself!)
      void plus1(int &val)
      // parameter must be a non-constant reference!
      // (call by value would be permitted, but you would not
      //    have any altered value after function call!)
      {
         val=val+1;
         // or: val+=1;
         // or: ++val;
         // or: val++;
         // prefix or postfix increment possible because only side effect wanted
      }

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