1.What is the output of the program
#include<stdio.h>
int main()
{
struct emp
{
char name[20];
int age;
float sal;
};
struct emp e = {"Tiger"};
printf("%d, %f\n", e.age, e.sal);
return 0;
}
A. 0, 0.000000
B. Garbage values
C. Error
D. None of above
Explanation:
When an automatic structure is partially initialized remaining elements are initialized to 0(zero).
If we use: printf("%s %d, %f\n", e.name, e.age, e.sal);
struct emp e = {“Tiger”, 5, 1500.50}; // Full Initialization
//Ouput: Tiger, 25, 1500.500000
struct emp e = {“Tiger”}; // Partial Initialization
//Ouput: Tiger, 0, 0.000000
struct emp e ; // No Initialization
//Ouput: GarbageValue, GarbageValue, GarbageValue!
2.What will be the output of the program?
#include<stdio.h>
int main()
{
printf("%d %d\n", 32<<1, 32<<0);
printf("%d %d\n", 32<<-1, 32<<-0);
printf("%d %d\n", 32>>1, 32>>0);
printf("%d %d\n", 32>>-1, 32>>-0);
return 0;
}
Explanation:
In case:
32<<1 means 0010 0000 are add +1 0100 0000 = 64.
32<<0 means 0010 0000 are add +0 0010 0000 = 32.
32<<-1 means 0010 0000 Zero -1 0000 0000 = 0.
32<<-0 means 0010 0000 L less -0 0010 0000 = 32.
32>>-1 means 0010 0000 Zero -1 0100 0000 = 64.
32>>-0 means 0010 0000 L less -0 0010 0000 = 0.
3.What will be the output of the program, if a short int is 2 bytes wide?
#include<stdio.h>
int main()
{
short int i = 0;
for(i<=5 && i>=-1; ++i; i>0)
printf("%u,", i);
return 0;
}
A. 1 … 65535
B. Expression syntax error
C. No output
D. 0, 1, 2, 3, 4, 5
Explanation:
for(i<=5 && i>=-1; ++i; i>0) so expression i<=5 && i>=-1 initializes for loop. expression ++i is the loop condition. expression i>0 is the increment expression.
In for( i <= 5 && i >= -1; ++i; i>0) expression i<=5 && i>=-1 evaluates to one.
Loop condition always get evaluated to true. Also at this point it increases i by one.
An increment_expression i>0 has no effect on value of i.so for loop get executed till the limit of integer (ie. 65535)
4.What will be the output of the program ?
#include<stdio.h>
int main()
{
static int arr[] = {0, 1, 2, 3, 4};
int *p[] = {arr, arr+1, arr+2, arr+3, arr+4};
int **ptr=p;
ptr++;
printf("%d, %d, %d\n", ptr-p, *ptr-arr, **ptr);
*ptr++;
printf("%d, %d, %d\n", ptr-p, *ptr-arr, **ptr);
*++ptr;
printf("%d, %d, %d\n", ptr-p, *ptr-arr, **ptr);
++*ptr;
printf("%d, %d, %d\n", ptr-p, *ptr-arr, **ptr);
return 0;
}
Explanation:
p is an array of pointers. ptr is a pointer to a pointer, initailly referring to p.
Step 1:
ptr++
ptr is incremented by 1, i.e. ptr now points to p+1 or (arr+1)
ptr-p=1, *ptr=arr+1, so ptr-arr=1, **ptr=(arr+1)=1
Step 2:
*ptr++
is *(ptr++), i.e. ptr=ptr+1=arr+2, the * part is not of any work here.
ptr-p=2, *ptr=arr+2, so ptr-arr=2, **ptr=(arr+2)=2
Step 3:
*++ptr
Similar to step 2, ++ptr=(++ptr)
ptr-p=3, *ptr=arr+3, so ptr-arr=3, **ptr=(arr+3)=3
Step 4:
++*ptr
is ++(*ptr), i.e. ptr now points to arr+4, but point to be noted that *p also changes,since ptr is pointer to p. Here ptr does not change its reference position unlike all the other steps, but changes the value it is pointing to
*p[]={arr, arr+1, arr+2, arr+4, arr+4}
so, ptr-p=3, *ptr=p[3]=arr+4, so ptr-arr=4, **ptr=(arr+4)=4
5.Point out the error in the program?
#include<stdio.h>
int main()
{
struct emp
{
char name[25];
int age;
float bs;
};
struct emp e;
e.name = "Suresh";
e.age = 25;
printf("%s %d\n", e.name, e.age);
return 0;
}
A. Error: Lvalue required/incompatible types in assignment
B. Error: invalid constant expression
C. Error: Rvalue required
D. No error, Output: Suresh 25
Explanation:
We cannot assign a string to a struct variable like e.name = “Suresh”; in C.
We have to use strcpy(char *dest, const char *source) function to assign a string.
Ex: strcpy(e.name, “Suresh”);