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C Language Questions And Answers Sample Test 4


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C Language Test 4


You have scored 3 out of 10
You Scored:2
Total Questions:2
Attended Questions:2
Correct Answered:2
1.
What will be the output of the program?

#include<stdio.h>
#define CUBE(x) (x*x*x)

int main()
{
    int a, b=3;
    a = CUBE(b++);
    printf("%d, %dn", a, b);
    return 0;
}



Explanation:

The macro function CUBE(x) (x*x*x) calculates the cubic value of given number(Eg: 103.)

Step 1: int a, b=3; The variable a and b are declared as an integer type and varaible b id initialized to 3.

Step 2: a = CUBE(b++); becomes

=> a = b++ * b++ * b++;

=> a = 3 * 3 * 3; Here we are using post-increement operator, so the 3 is not incremented in this statement.

=> a = 27; Here, 27 is store in the variable a. By the way, the value of variable b is incremented by 3. (ie: b=6)

Step 3: printf("%d, %dn", a, b); It prints the value of variable a and b.

Hence the output of the program is 27, 6.


2.
What do the following declaration signify?

char *arr[10];





3.
Which of the following statements are correct about 6 used in the program?
int num[6];
num[6]=21;





4.
What will be the output of the program in DOS (Compiler - Turbo C)?

#include<stdio.h>
double i;

int main()
{
    (int)(float)(char) i;
    printf("%d", sizeof((int)(float)(char)i));
    return 0;
}



Explanation:

Due to the C language is being platform dependent:

In Turbo C (DOS - 16 bit platform), the output will be 2.

But in GCC (Unix/Linux - 32 bit platform), the output will be 4.


5. What will be the output of the program if the array begins at 65472 and each integer occupies 2 bytes?
#include<stdio.h>

int main()
{
    int a[3][4] = {1, 2, 3, 4, 4, 3, 2, 1, 7, 8, 9, 0};
    printf("%u, %un", a+1, &a+1);
    return 0;
}





6.
In which stage the following code 
#include<stdio.h> 
gets replaced by the contents of the file stdio.h



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.


7.
   What will be the output of the program ?

#include

int main()
{
    char *str;
    str = "%s";
    printf(str, "Kn");
    return 0;
}





8.
What will be the output of the program ?

#include<stdio.h>
void fun(int **p);

int main()
{
    int a[3][4] = {1, 2, 3, 4, 4, 3, 2, 8, 7, 8, 9, 0};
    int *ptr;
    ptr = &a[0][0];
    fun(&ptr);
    return 0;
}
void fun(int **p)
{
    printf("%dn", **p);
}





9.
What will be the output of the program?

#include<stdio.h>

int main()
{
    const int x=5;
    const int *ptrx;
    ptrx = &x;
    *ptrx = 10;
    printf("%dn", x);
    return 0;
}



Explanation:

Step 1: const int x=5; The constant variable x is declared as an integer data type and initialized with value '5'.

Step 2: const int *ptrx; The constant variable ptrx is declared as an integer pointer.

Step 3: ptrx = &x; The address of the constant variable x is assigned to integer pointer variable ptrx.

Step 4: *ptrx = 10; Here we are indirectly trying to change the value of the constant vaiable x. This will result in an error.

To change the value of const variable x we have to use *(int *)&x = 10;


10.
What do the following declaration signify?

int (*pf)();





11.
What will be the output of the program?

#include<stdio.h>
int fun(int **ptr);

int main()
{
    int i=10;
    const int *ptr = &i;
    fun(&ptr);
    return 0;
}
int fun(int **ptr)
{
    int j = 223;
    int *temp = &j;
    printf("Before changing ptr = %5xn", *ptr);
    const *ptr = temp;
    printf("After changing ptr = %5xn", *ptr);
    return 0;
}





12.    What is (void*)0?





13.
What do the following declaration signify?

int *f();





14.
What will be the output of the program?

#include<stdio.h>

int main()
{
    char huge *near *far *ptr1;
    char near *far *huge *ptr2;
    char far *huge *near *ptr3;
    printf("%d, %d, %dn", sizeof(ptr1), sizeof(*ptr2), sizeof(**ptr3));
    return 0;
}





15.
What will be the output of the program in TurboC?

#include<stdio.h>
int fun(int **ptr);

int main()
{
    int i=10, j=20;
    const int *ptr = &i;
    printf(" i = %5X", ptr);
    printf(" ptr = %d", *ptr);
    ptr = &j;
    printf(" j = %5X", ptr);
    printf(" ptr = %d", *ptr);
    return 0;
}





16.
What do the following declaration signify?

int *ptr[30];





17.
What will be the output of the program?

#include<stdio.h>

int main()
{
    const int i=0;
    printf("%dn", i++);
    return 0;
}



Explanation:

This program will show an error "Cannot modify a const object".

Step 1: const int i=0; The constant variable 'i' is declared as an integer and initialized with value of '0'(zero).

Step 2: printf("%dn", i++); Here the variable 'i' is increemented by 1(one). This will create an error "Cannot modify a const object".

Because, we cannot modify a const variable.


18.
   What will be the output of the program ?

#include

int main()
{
    float arr[] = {12.4, 2.3, 4.5, 6.7};
    printf("%dn", sizeof(arr)/sizeof(arr[0]));
    return 0;
}





19.
    What will be the output of the program?

#include
#define PRINT(i) printf("%d,",i)

int main()
{
    int x=2, y=3, z=4;
    PRINT(x);
    PRINT(y);
    PRINT(z);
    return 0;
}



Explanation:

The macro PRINT(i) print("%d,", i); prints the given variable value in an integer format.

Step 1: int x=2, y=3, z=4; The variable x, y, z are declared as an integer type and initialized to 2, 3, 4 respectively.

Step 2: PRINT(x); becomes printf("%d,",x). Hence it prints '2'.

Step 3: PRINT(y); becomes printf("%d,",y). Hence it prints '3'.

Step 4: PRINT(z); becomes printf("%d,",z). Hence it prints '4'.

Hence the output of the program is 2, 3, 4.


20. If a variable is a pointer to a structure, then which of the following operator is used to access data members of the structure through the pointer variable?





21. How many bytes are occupied by near, far and huge pointers (DOS)?



Explanation:

near=2, far=4 and huge=4 pointers exist only under DOS. Under windows and Linux every pointers is 4 bytes long.


22.
     What will be the output of the program?

#include
typedef void v;
typedef int i;

int main()
{
    v fun(i, i);
    fun(2, 3);
    return 0;
}
v fun(i a, i b)
{
    i s=2;
    float i;
    printf("%d,", sizeof(i));
    printf(" %d", a*b*s);
}





23.
What do the following declaration signify?

char **argv;





24.
Can you combine the following two statements into one?

char *p;
p = (char*) malloc(100);





25. What will happen if in a C program you assign a value to an array element whose subscript exceeds the size of array?





26.
What will be the output of the program?

#include<stdio.h>
#define SQR(x)(x*x)

int main()
{
    int a, b=3;
    a = SQR(b+2);
    printf("%dn", a);
    return 0;
}



Explanation:

The macro function SQR(x)(x*x) calculate the square of the given number 'x'. (Eg: 102)

Step 1: int a, b=3; Here the variable a, b are declared as an integer type and the variable b is initialized to 3.

Step 2: a = SQR(b+2); becomes,

=> a = b+2 * b+2; Here SQR(x) is replaced by macro to x*x .

=> a = 3+2 * 3+2;

=> a = 3 + 6 + 2;

=> a = 11;

Step 3: printf("%dn", a); It prints the value of variable 'a'.

Hence the output of the program is 11


27.
      What will be the output of the program ?

#include

int main()
{
    int i=3, *j, k;
    j = &i;
    printf("%dn", i**j*i+*j);
    return 0;
}





28. In C, if you pass an array as an argument to a function, what actually gets passed?



Explanation:

The statement 'C' is correct. When we pass an array as a funtion argument, the base address of the array will be passed.


29.
Declare the following statement?
"An array of three pointers to chars".





30.
    What will be the output of the program ?

#include

int main()
{
    char str[20] = "Hello";
    char *const p=str;
    *p='M';
    printf("%sn", str);
    return 0;
}







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