C Linux interview questions and answers

C Linux interview questions and answers

(1)What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

    int a=5;

    printf("%d %d %d",a++,a++,++a);

    return 0;

}

Output:

In LINUX GCC compiler

7 6 8

In TURBO C

7 6 6

In Turbo C, parameters are passed from right to left in the printf function, whereas in Linux, the standard convention is to pass parameters from left to right.

(2)What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

    int a=5,b=10,c=15,d=20;

    printf("%d %d %d");

        return 0;

}

Output:

In LINUX GCC compiler

Garbage values

In TURBO C

5 10 15

Hints: Local variables are stored on the stack in C programming.

(3) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

    int i=5,j=5,y;

    int x=++i + ++i + ++i;

    y=++j + ++j + ++j;

    printf("%d  %d  %d %d",x,y,i,j);

    return 0;

}

Output:

In LINUX GCC compiler
22  22  8  8

In TURBO C

21  24  8  8

(4) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

        int  near *p;

        int  far *q;

        int  huge *r;

        printf("%d  %d  %d",sizeof(p),sizeof(q),sizeof(r));

        return 0;

}

Output:

In LINUX GCC compiler

Compilation error

In TURBO C

2  4  4

Note: In Linux, the concepts of near, far, and huge pointers, commonly used in some other systems, are not applicable

(5) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

    char *p;

    int *q;

    float **r;

    printf("%d  %d  %d",sizeof(p),sizeof(q),sizeof(r));

    return 0;

}

Output:

In LINUX GCC compiler

4  4  4

In TURBO C

2  2  2

Hints: In Linux, the size of any type of pointer is typically 4 bytes, while in Turbo C, it is 2 bytes.

(6) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

    short int a=5;

    int b=5;

    long int c=5l;

    float d=5.0f;

    double e=5.0;

    long double f=5.0L;

    char g='5';

    printf("Size of short int: %d\n",sizeof(a));

    printf("Size of int: %d\n",sizeof(b));

    printf("Size of long int: %d\n",sizeof(c));

    printf("Size of float: %d\n",sizeof(d));

    printf("Size of double: %d\n",sizeof(e));

    printf("Size of long double: %d\n",sizeof(f));

    printf("Size of char: %d\n",sizeof(g));

        return 0;

}

Output:
In LINUX GCC compiler

Size of short int: 2

Size of int: 4

Size of long int: 4

Size of float: 4

Size of double: 8

Size of long double: 12

Size of char: 1

In TURBO C

Size of short int: 2

Size of int: 2

Size of long int: 4

Size of float: 4

Size of double: 8

Size of long double: 10

Size of char: 1

(7) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

    int main(){

        int a=300;

    char *p=(char *)&a;

        printf("%d\n",*p);

    printf("%d",*++p);

        return 0;

}

Output:

In LINUX GCC compiler

44

1

In TURBO C

44

1

(8) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

    char c='A';

    printf("%d   %d",sizeof(c),sizeof('A'));

    return 0;

}

Output:

In LINUX

1  4

In TURBO C

1  2

(9) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

    enum color{RED,BLUE,GREEN=-2,YELLOW,PINK};

    printf("%d  %d",BLUE,PINK);

    return 0;

}

Output:

In LINUX GCC compiler

1 0

In TURBO C

1 0

(10) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

    char c=127;

    printf("%d",++c);

    printf("  %d",++c);

    return 0;

}

Output:

In LINUX GCC compiler

-128 -127

In TURBO C

-128 -127

Hints: char data type cyclic property.

(11) What will be output if you will execute following program by gcc compiler in Linux?

#include"stdio.h"

struct info1{

    char *title;

    long int size;

    double grade;

}hero1;

union info2{

        char *title;

        long int size;

        double grade;

}hero2;

int main(){

    printf("Size of structure: %d\n",sizeof(hero1));

    printf("Size of union:  %d",sizeof(hero2));

    return 0;

}

Output:

In LINUX GCC compiler

Size of structure: 16

Size of union:  8

In TURBO C

Size of structure: 14

Size of union:  8

(12) What will be output if you will execute following program by gcc compiler in Linux?

#define size(x) (char *)(x+1)-(char *)x

#include<stdio.h>

int main(){

    long int *p;

    long double *q;

        printf("Size of long int: %d\n",size(p));

    printf("Size of long double: %d",size(q));

        return 0;

}

Output:

In LINUX GCC compiler

Size of long int: 4

Size of long double: 12

In TURBO C

Size of long int: 4

Size of long double: 10

(13) What will be output if you will execute following program by gcc compiler in Linux?

#include<stdio.h>

int main(){

      int i=2,j=5,k=3;

      int a=i&&j>=k;

      printf("%d",a);

      return 0;

}

Output:

In LINUX GCC compiler

1

In TURBO C

1

Hints: In C programming, conditional and relational operators return 1 if the condition is true; otherwise, they return 0.

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