C Pre-Processor - Aptitude Questions & Answers

#include <stdio.h>
int main()
{
#ifdef debug
	printf("Start debugging...");
#endif
	printf("IncludeHelp");
	return 0;
}

1. Start debugging...IncludeHelp
2. IncludeHelp
3. Error
4. debug

#include <stdio.h>
#define MAX 100
int main()
{
#define MAX 20
printf("MAX=%d...",MAX);
return 0;
}

1. Error
2. MAx=100...
3. MAx=20...
4. MAX=10020

#include <stdio.h>
#define FUN(x)	x*x
int main()
{
int val=0;
val=128/FUN(8);
printf("val=%d",val);
return 0;
}

1. 2
2. 128
3. 64
4. 1

#include <stdio.h>
#define FUN(x,y)	x##y
int main()
{
int a1=10,a2=20;
printf("%d...%d",FUN(a,1),FUN(a,2));
return 0;
}

1. Error
2. 10...10
3. 20...20
4. 10...20

#include <stdio.h>
#define LARGEST(x,y)	(x>=y)?x:y
int main()
{
	int a=10,b=20,l=0;
	l=LARGEST(a++,b++);

	printf("a=%d,b=%d,largest=%d",a,b,l);
	return 0;
}

1. a=10,b=20,largest=20
2. a=11,b=21,largest=20
3. a=11,b=21,largest=21
4. a=11,b=22,largest=21

#include <stdio.h>

#define OFF 0
#if debug == OFF
	int a=11;
#endif

int main()
{
	int b=22;
	printf("%d...%d",a,b);
	return 0;
}

1. 11...22
2. Error
3. 11...11
4. 22...22

#include <stdio.h>
#define TEXT IncludeHelp
int main()
{
	printf("%s",TEXT);
	return 0;
}

1. IncludeHelp
2. TEXT
3. Error
4. TEXT IncludeHelp

#include <stdio.h>
#define VAR1	VAR2+10
#define	VAR2	VAR1+20

int main()
{
	printf("%d",VAR1);
	return 0;
}

1. VAR2+10
2. VAR1+20
3. Error
4. 10

#include <stdio.h>

#define SUM(x,y)	int s; s=x+y; printf("sum=%d\n",s);
int main()
{
	SUM(10,20);
	return 0;
}

1. sum=30
2. 10,20
3. Error
4. sum=0

#include <stdio.h>
#define MAX	99
int main()
{
	printf("%d...",MAX);
#undef MAX
	printf("%d",MAX);
	return 0;
}

1. 99...0
2. 99...99
3. Error
4. MAX...MAX