## INDEX

### C questions and answers

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C questions and answers with explanation
4. Arrays            5. Loops                  5. Preprocessor
7. printf            8. Variables              7. File handling
C questions and answers for interview

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### C interview questions and answers

C interview questions and answers for freshers. It is basic c language technical frequently asked interview questions and answers. It includes data structures, pointers interview questions and answers for experienced
Interview questions and answer of C with explanation for fresher

1
Write a c program to print Hello world without using any semicolon.
Explanation:
Solution: 1
void main(){
if(printf("Hello world")){
}
}

Solution: 2
void main(){
while(!printf("Hello world")){
}
}

Solution: 3
void main(){
switch(printf("Hello world")){
}
}

2
Swap two variables without using third variable.
Explanation:
#include<stdio.h>
int main(){
int a=5,b=10;
//process one
a=b+a;
b=a-b;
a=a-b;
printf("a= %d  b=  %d",a,b);

//process two
a=5;
b=10;
a=a+b-(b=a);
printf("\na= %d  b=  %d",a,b);
//process three
a=5;
b=10;
a=a^b;
b=a^b;
a=b^a;
printf("\na= %d  b=  %d",a,b);

//process four
a=5;
b=10;
a=b-~a-1;
b=a+~b+1;
a=a+~b+1;
printf("\na= %d  b=  %d",a,b);

//process five
a=5,
b=10;
a=b+a,b=a-b,a=a-b;
printf("\na= %d  b=  %d",a,b);
return 0;
}

3
What is dangling pointer in c?
Explanation:
Dangling pointer:

A dangling pointer arises when it continues to reference a memory address that once held a variable but has since been deallocated. This situation is commonly referred to as the dangling pointer problem.

Initially:

Later:
For example:

What will be output of following c program?

#include<stdio.h>

int *call();
int main(){

int *ptr;
ptr=call();

fflush(stdin);
printf("%d",*ptr);
return 0;
}
int * call(){

int x=25;
++x;

return &x;
}

Output: Garbage value

Note: Certain compilers may issue a warning message when returning the address of a local variable or a temporary.

Explanation: The variable 'x' is a local variable, confined to the scope and lifetime of the function call. Consequently, after returning the address of 'x', the variable 'x' becomes invalid, while the pointer 'ptr' persists in pointing to that location.

Solution of this problem:
Make the variable x is as static variable. In other word we can say a pointer whose pointing object has been deleted is called dangling pointer.

#include<stdio.h>

int *call();
int main(){
int *ptr;
ptr=call();

fflush(stdin);
printf("%d",*ptr);
return 0;
}
int * call(){

static int x=25;
++x;

return &x;
}

Output: 26

4
What is wild pointer in c?
Explanation:
An uninitialized pointer in C is commonly referred to as a "wild pointer."
Example:

What will be output of following c program?

int main(){
int *ptr;
printf("%u\n",ptr);
printf("%d",*ptr);
return 0;
}