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C Programming - C Preprocessor

Exercise : C Preprocessor - General Questions
1.
What will the SWAP macro in the following program be expanded to on preprocessing? will the code compile? 
#include<stdio.h>
#define SWAP(a, b, c)(c t; t=a, a=b, b=t)
int main()
{
    int x=10, y=20;
    SWAP(x, y, int);
    printf("%d %d\n", x, y);
    return 0;
}
It compiles
Compiles with an warning
Not compile
Compiles and print nothing
Answer: Option
Explanation:
The code won't compile since declaration of t cannot occur within parenthesis.
2.
In which stage the following code
#include<stdio.h>
gets replaced by the contents of the file stdio.h
During editing
During linking
During execution
During preprocessing
Answer: Option
Explanation:

The preprocessor replaces the line #include <stdio.h> with the system header file of that name. More precisely, the entire text of the file 'stdio.h' replaces the #include directive.

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