C Programming Aptitude Set-1 with answer

C Programming Aptitude Question Set-1 (with output and justification)

Predict the output of following programs with justification.

Question - 1

#include<stdio.h>

int main()

{

    char name[ ]="INDIA";

    int i;

           

    for(i=0; name[i]; i++)

       printf("%c%c%c ",name[i],*(name+i),*(i+name));

    return 0;

}

/*

Output:

III NNN DDD III AAA

Justification: name[i], *(name+i) and *(i+name) are evaluated to same value.

*/

Question - 2

#include<stdio.h>

int main()

{

    int const marks=5;

    printf("%d",marks++);

    return 0;

}

/*

Output: Compiler error

Justification: Cannot modify a constant value.

*/

Question - 3

#include<stdio.h>
int main()
{
  static int number = 3;
  printf("%d ",number--);

  if(number)
main();

  return 0;
}

/*

Output:

3 2 1

Justification:

static storage class is initialized once. The value of a static variable is retained even between the function calls. Main is also function, which can be called recursively. This main function will be called until

value of number remains true(i.e. > 0)

*/

Question - 4

#include<stdio.h>
int main()
{
  float number1 = 5.1;
  double number2 = 5.1;
  if(number1 == number2)
printf("Equal numbers.");
  else
printf("Not equal numbers.");

}

/*

Output:

Not equal numbers.

Justification:

Values of floating point numbers (float, double, long double) are rounded after its defined precision value. Float takes 4 bytes and long double takes 10 bytes. So precision(rounded) value of float is different than long double.

Note: Be cautious while using floating point numbers with relational operators like == , >, <, <=, >= and != .

*/

Question - 5

#include<stdio.h>

int main()

{

   char ch='A';

   switch(ch)

   {

      default : printf("Error");

      case 'A': printf("Hello - A");

                break;

      case 'B': printf("Hello B");

                break;

      case 'C': printf("Hello C");

                break;

   }

}

/*

Output : Hello - A

Justification:

default case can be placed anywhere inside the loop. It will be executed only when other cases does not match.

*/