Isn’t C the first programming language you studied during your school days? Most of you might have studied it during your beginning lessons in programming. C is the most basic programming language with a wide variety of applications.
The following questions are some of the most commonly asked top 10 C Programming Interview questions and answers. You can review the kind of questions you’ll be asked in your interview from these C interview questions.
Why wait then? Let us move towards the questions and try to get a job as a C developer working on real-world data projects.
1. According to you, is C a high-level or mid-level programming language?
As far as I know, C is a mid-level programming language, a union of both high-level and low-level languages. Machine-level and assembly languages fall in the low-level programming language category whereas human language such as English is a high-level language.
A programmer can use C language to do both, system programming like operating system code and application programming.
2. Can you differentiate between #include “…” and #include <…>?
The preprocessor in C includes the file in our C program.
- #include <…>
You must use #include <…> to include predefined header files or system header files in your program. We write the name of the predefined header file inside the angular “<>” brackets. The preprocessor can find these standard library header files at default locations like /usr/include or /usr/local/include.
Example
// C program to illustrate #include <…>
#include <stdio.h>
int main()
{
printf(“Welcome to C Programming “);
return 0;
}
Output
Welcome to C Programming
- #include “…”
If you have to define your own header files, use #include “…”. You have to mention the name of your written header file in quotes “…”. In this method, the preprocessor searches for the user-defined header files in the same directory or -I defined folders where the source file is present, and afterward to the standard directories pre-designated by the compiler.
Example
prod.h Header file:
int prod(int x, int y)
{
return(x * y);
}
// C program to illustrate #include “…”
#include “prod.h”
int main()
{
int x = 60;
int y = 30;
// Invoke the function defined in the header file
int z =prod(x, y);
printf(“%d”, z);
return 0;
}
Output
1800
3. Explain some of the characteristics of the C language.
- Mid-level language: combines features of both, high and low-level languages.
- Procedural language: C contains step-by-step instructions to perform a specific task.
- Portable: You can write and run your C program code on any operating system with minimal modifications.
- Extensible: One can easily add new features to the prewritten C program.
- Statically typed language: You have to declare the type of the variables in C before compiling your program. The compiler checks the variable type during compilation instead of run time.
- General purpose language: C can be used for developing different types of applications be it OS or application programming, or tools like uptime monitoring and website monitoring software.
4. Explain format specifiers in C.
Format specifiers inform the C compiler regarding the type of data value stored in a variable during input and output operations. They are used with the “%” symbol in the formatted string in functions such as printf(), scanf, sprintf(), etc.
Below is the list of the commonly used format specifiers in the C language:
| Format Specifiers | Type of Value |
| %d | Signed integer |
| %c | character |
| %f | float |
| %s | string |
| %p | pointer |
| %i | Signed integer |
5. Differentiate between global variables and local variables in C.
| Global Variables | Local Variables |
| It’s the variable declared outside any function or block | It’s the variable declared inside a function or a block |
| Stores 0 as the default value | Stores garbage value by default |
| Its validity is limited to the block or function in which it’s declared | It’s valid until the program execution |
| The compiler determines the storage place of local variables | If you don’t specify the storage place, it gets stored inside the stack |
| You can access the global variable anywhere inside the program. | You can access the local variable only inside the block or function it’s declared in. |
6. How will you explain the volatile keyword in C?
The volatile keyword associated with a variable at the time of declaration indicates that its value is temporary. It can change at any time.
Syntax
volatile data_type variable_name;
7. How will you create an infinite for loop in C?
An infinite for loop gets created when the test condition never becomes false or when you forget to add the test condition in the for loop. Let’s understand with an example.
Example of an infinite for loop in C
#include <stdio.h>
int main() {
for (;;) {
printf(“Welcome to C Programming”);
}
return 0;
}
Output
Welcome to C Programming
Welcome to C Programming
Welcome to C Programming
…
You can see that the above code prints the same lines infinitely. It’s because we haven’t mentioned the test condition in the for loop.
8. Can you describe the concept of garbage value in C?
A garbage value is a value assigned randomly to an uninitialized variable in a C program.
Example
#include<stdio.h>
int main() {
int var;
printf(“The value of var: %d “, var);
return 0;
}
Output
The value of var: 0
In the above C program, we declared an integer variable var but didn’t assign any value to it. During program execution, it prints 0 as the value of the variable. This value is the garbage value stored in the memory.
9. Explain structures in C.
The structure is a user-defined derived data type in C. It’s a collection of different types of variables. The memory allocated for the structure data type is the total of the memory of individual members. The structure variables or objects let you access the structure members using the.
Syntax of structure
struct structure_name
{ datatype variable1;
datatype variable2;
datatype variable3;
}[structure variables];
Example
struct employees
{ int empId;
char name[10];
int age;
} emp1, emp2;
The structure employees contain information regarding two employees that can be accessed using the structure variables, emp1 and emp2.
10. Is it possible to compile a program in C in the absence of the main() function?
Yes, it is possible to compile a C program without the main() function though we cannot execute it.
Conclusion
The above-discussed questions are expertly designed taking into consideration various aspects of the interview faced by the aspiring developers. These are the most basic ones which you can even go through just an hour before you enter the interview room.
Knowing the C language has numerous advantages. Hence, practice as much as possible before facing the interview.
Read about the 60 questions to ask in an interview
