Updated June 16, 2023
Introduction to C Programming Interview Questions
The following article provides an outline for C Programming Interview Questions. C programming is essential for any interviewer because it is used for development. C programming includes a different concept that is used while developing software. In other words, we can say that it is a high-level structured-oriented language, and it is used for general-purpose development. We have a different library in C programming and can add user-defined functions during development.
Part 1 – C Programming Interview Questions (Basic)
Let us now have a look at the Basic C Programming Interview Questions:
Q1. What are the different features offered by programming Language C?
Answer:
The different features offered by programming Language C are:
- C is a structured programming language with actual flow control construction.
- It is a simple and versatile language.
- C has a rich set of operators.
- It has only 32 keywords.
- It is a highly portable programming language.
- It has several predefined functions.
- Programs written in C are efficient and fast.
- C permits all data conversions and mixed-mode operations.
- Dynamic memory allocation is possible in C.
- Extensive varieties of data types, such as arrays, pointers, structures, and unions, are available in C.
- It efficiently manipulates bits, bytes, and addresses.
- A recursive function is possible in C.
- The c compiler combines the capability of an assembly-level language with the features of a high-level language.
Q2. Why is C Programming Language so popular?
Answer:
C Programming Language is so popular because of the following reasons:
- Programmers can control, allocate, and deallocate memory.
- Using malloc and calloc function, memory is allocated statically, automatically, or dynamically.
- C sits close to the operating system.
- It is used widely in operating systems, network drivers, system utilities, language compilers, and language interpreters.
Q3. What is a Null pointer in C?
Answer:
Null is a special reserved value of a C. Null pointer differs from an uninitialized and dangling arrow.
Q4. How will you define stack in C?
Answer:
One type of data structure is the stack. A data structure called a stack stores data in a specific order. The FILO (First In, Last Out) method stores data in stacks. Data retrieval is called a POP, whereas storage in a stack is called a PUSH. In any given instance, only the top of the pile is accessible; therefore, the stored data should be extracted first to get the rest of the stack’s contents.
Q5. Write a C program to print: This is my first program in C.
Answer:
Given below is the program mentioned:
Code:
#include <stdio.h>
int main()
{
printf("Hello, This is my first program in C ");
return 0;
}
// printf() displays the string inside quotation
Q6. What is the major difference between FOR and WHILE loops?
Answer:
The major difference between FOR and WHILE loops are as follows:
- FOR and WHILE loops are entry-controlled loops which means the test condition is checked for truth while entering into the loop’s body.
- The FOR loop is usually appropriate for loops where the initialization and increment are single statements and logically related. In contrast, the WHILE loop keeps the loop control statements together in one place.
- FOR loop is used in a more compact case comparing the WHILE loop.
Q7. What is the difference between the = symbol and == symbol?
Answer:
The difference between the = symbol and == symbol is as follows:
- The = symbol is often used in mathematical operations while == symbol is a relational operator.
- = Symbol is used to assign a value to a given variable while == symbol is used to compare two values.
Q8. What are the different data types associated with programming Language C?
Answer:
The different data types associated with programming Language C are:
- Int: Integer-Representing number.
- Float: Representing Numbers with a fraction part.
- Double: Double-precision floating-point value.
- Char: Representing a single character.
- Void: Special purpose type without any value.
Q9. What is the difference between ++x and x++?
Answer:
The difference between ++x and x++ is as follows:
- ++X is called a prefixed increment, and the increment will happen first on the X variable.
- X++ is called postfix increment, and the increment happens after the value of the X variable used for the operations.
Q10. What is a sequential access file?
Answer:
Programs store data into files and retrieve existing data from files only. With the sequential access file, such data is saved in a sequential pattern. When retrieving data from such files, each must be read one by one until the required information is found.
Q11. What is a nested loop?
Answer:
A nested loop is a loop that runs within another loop. For example, you can have an inner loop that is inside an outer loop. In this scenario, the inner loop is performed a number of times as specified by the outer loop. The inner loop is first performed for each turn on the outer loop.
Q12. What are the differences between static and dynamic library linking?
Answer:
The differences between static and dynamic library linking are as follows:
- Static Linking is the process of copying all library modules used in the program into the final executable image. In contrast, in Dynamic Linking, the names of the external libraries are placed in the final executable file. At the same time, the actual linking takes place at runtime when both executables file and libraries are placed in the memory.
- Static Linking is performed by programs called linkers as the last step in compiling a program, while Dynamic Linking is performed at runtime by the operating system.
- Statically linked files are significantly larger in size when compared to Dynamic Linking files.
- Static Linking consumes more memory and disk space, while Dynamic Linking saves memory and space.
- The statically linked program takes constant load time every time it is loaded into the memory for execution, while in dynamic linking, load time might be reduced if the shared library code is already present in memory.
Q13. What is the difference between call by value and call by reference in C language?
Answer:
The difference between call by value and call by reference in C language are as follows:
- In call by value, a copy of actual arguments is passed to formal arguments of the called function while in a call by reference, the location (address) of actual arguments is passed to formal arguments of the called function.
- In call by value, actual arguments will remain safe; they cannot be modified accidentally. In a call by reference, alteration to actual arguments is possible within from called function; therefore, the code must handle arguments carefully, or else you will get unexpected results.
Q14. How many types of features are available in the C programming language?
Answer:
Basically, there are 6 main types of features.
- Simple: Normally C programming is very simple programming because it uses structured patterns. This means the program is divided into different parts.
- Portable: The portable is one of the most important features of C; once we write a program, it can be run on any system with some modification.
- Mid Level: This is a mid-level programming language that combines the features of a high-level language.
- Fast Speed: It is a very fast programming language because it includes data types and operators.
- Memory Management: It has inbuilt memory management functions, so it helps to save memory and improve efficiency.
- Extensible: It adopts new features easily.
Q15. What are the different type’s format specifiers in C programming?
Answer:
Basically, there are four types of specifiers as follows:
- %d: It is used to print the integer values.
- %s: It is used to print the string.
- %c: It is used to print the character value.
- %f: It is used to print the floating-point numbers.
Q16. What is the difference between a global variable and a local variable?
Answer:
Given below is the difference mentioned:
Global Variable |
Local Variable |
Declaration of the variable is outside the function. | Declaration of the variable is inside the function. |
The scope of this variable is throughout the code. | The scope of this variable is to specify a function. |
The global variable we can access is the whole program. | A local variable can be an accessible-only statement declared inside the function. |
The compiler will decide the storage of location. | On the other hand, the stack will decide the local variable storage location. |
Q17. Why do we use static variables in C?
Answer:
Basically, those variables we declare as static it is called a static variable. Mainly we use static variables because of scope; the scope of static variables is present throughout the program. Another reason is that if we want to use a common value, then we can also use a static variable.
Part 2 – C Programming Interview Questions (Advanced)
Let us now have a look at the Advanced C Programming Interview Questions:
Q18. Why do we use a function in C?
Answer:
Basically, the function is used to avoid the duplication of code, which means we can use the same code again when required. One more benefit of function is that when we use functions, it is easily understandable to others.
Q19. What is call by value?
Answer:
Call by value means we can pass another value to the function instead of the original values, which means without modification of original values.
Q20. What is call by reference?
Answer:
In call by reference, when we pass duplicate values to the functions, then the original values will be modified.
Q21. What is an array?
Answer:
Basically, an array is nothing but a similar kind of element we can store in a contiguous location as well as it also helps us to optimize the code. There are two types of arrays such as one-dimensional arrays and multidimensional arrays.
Q22. What is a pointer?
Answer:
This is another technique to optimize the code which means the variable refers to the address of values. When we declare a variable while coding, the system allocates the memory which we can fetch with the help of pointers.
Q23. What is malloc() and calloc() function in C?
Answer:
If we want to allocate more than one block of memory, then we can use the malloc() function. On the other hand, if we have a single block of memory, then we can use the calloc() function.
Q24. What are the benefits of structure?
Answer:
Basically, the structure is used to define the user-defined data type, which is used to store the different types of values in a single unit.
Q25. Can we execute the program without the main() function?
Answer:
Yes, we can compile, but we can’t execute without the main() function. But another way to execute the program without a main is that we need to use the #defined keyword while writing the program.
Q26. What is a token, and why do we use it in C?
Answer:
Basically, a token is nothing but the identifier, or we can say that it is a small unit of a C program used to execute the specified statements. C provides the different types of tokens such as identifiers, keywords, constants, operators and special characters, etc.
Q27. Do you know a command line argument?
Answer:
When we pass an argument to the main() function at the time of program execution, it is called a command line argument.
Q28. Is there any difference between the getch() and getche()?
Answer:
Basically, getch() function is used to read a single character from the user, and there is no buffer. It does not display any output on the screen. On the other hand, getche() also reads in single characters, but it is used to display output on the screen.
Q29. Can you write syntax to declare functions in C?
Answer:
Given below is the syntax to declare functions in C:
specified function name(required all parameters list){
Body of function ;
}
Q30. Which function is used to convert the small case to the upper case?
Answer:
Basically, C provides the toupper() function to convert the small case to the upper case.
Q31. Can you write the code to generate random numbers in C?
Answer:
Given below is the code to generate random numbers in C:
#include
int main(){
int num1,num2;
for(num1=1;num1=10;num1++){
num2=rand();
printf("%dn", num2);
}
return 0;}
Q32. Can we create a head file that we require that is customized implementation?
Answer:
Yes, we can create a customized header file as per our requirement; for implementation, we need to use #include.
Q33. What is a memory leak?
Answer:
Leak means the system cannot free the allocated space after completing the code.
Q34. Do you typecast in C?
Answer:
Yes, Typecasting means it is a process to convert one data type to another data type.
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