Predict the output or error(s) for the following:

1)

#include <stdio.h>

#define a 10

main()

{

#define a 50

printf("%d",a);

}

Answer:

50

Explanation:

The preprocessor directives can be redefined anywhere in the program. So the most recently assigned value will be taken.

2)

#define clrscr() 100

main()

{

clrscr();

printf("%d\n",clrscr());

}

Answer:

100

Explanation:

Preprocessor executes as a seperate pass before the execution of the compiler. So textual replacement of clrscr() to 100 occurs.The input  program to compiler looks like this :

        main()

{

100;

printf("%d\n",100);

}

Note:  100; is an executable statement but with no action. So it doesn't give any problem