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
Hints: In Turbo c parameter is passed from right to left in printf function but not in the Linux.
(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 stores in the stack.
(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
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 there is not any concept of near, far and huge pointers
(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: size of any type of pointer in Linux is 4 and in turbo c is 2.
(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
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: Any conditional or relational operator returns 1 if condition is true otherwise it returns 0.
If you have any queries or suggestions in above c Linux interview questions, please share it.
