MACRO AND FUNCTION

Introduction

While writing the macro, you have to write the macro body carefully because the macro just indicates replacement, not the function call.

Program

#include  #define add(x1, y1)  x1+y1   //E #define mult(x1,y2) x2*y2   //F main () {     int a,b,c,d,e;     a = 2;     b = 3;     c = 4;     d = 5;     e = mult(add(a, b), add(c, d)); //A      // mult(a+b, c+d)               //B     // a+b * c+d                    //C      printf ("The value of e is %d\n", e); } 

Explanation

1. Statement E indicates a macro for adding two numbers.

2. Statement F indicates a macro for multiplying two numbers.

3. Statement A indicates a macro that is supposed to add two numbers and then multiply two numbers. In this case, it is supposed to perform the calculation (2+3) * (4+5).

4. The actual expansion of macro adds is given in statement B.

5. The final expansion of mult gives the expansion a+b * c+d, which is erroneous.

6. The final value of e is 17, which is not correct.

7. To get the correct value, use the following definition:

   #define add(x1, y1) (x1+y1) #define mult(x2, y2) (x2*y2) 

Point to Remember

While using the macro, you have to write the expression correctly. You can use parentheses to give the correct meaning to the expression.