C Interview Questions and Answers

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C Interview Questions and Answers

In this article, I am going to discuss C Interview Questions and Answers. Here, as part of this article, we are going to discuss the top 50 C Programming Language Interview Questions along with Answers.

What are the key features in the C programming language?

Features are as follows:
Portability: It is a platform-independent language.
Modularity: Possibility to break down large programs into small modules.
Flexibility: The possibility of a programmer to control the language.
Speed: C comes with support for system programming and hence it compiles and executes with high speed when compared with other high-level languages.
Extensibility: Possibility to add new features by the programmer.

What are the basic data types associated with C?

Int – Represent the number (integer)
Float – Number with a fraction part.
Double – Double-precision floating-point value
Char – Single character
Void – Special purpose type without any value.

What is the description for syntax error?

The mistakes/errors that occur while creating a program are called syntax errors. Misspelled commands or incorrect case commands, an incorrect number of parameters in calling method /function, data type mismatches can be identified as common examples for syntax errors.

What is the process to create increment and decrement statement in C?

There are two possible methods to perform this task.

1. Use increment (++) and decrement (-) operator. Example When x=4, x++ return 5 and x- returns 3.
2. Use conventional + or – sign. Example When x=4, use x+1 to get 5 and x-1 to get 3.

What are reserved words with a programming language?

The words that are a part of the standard C language library are called reserved words. Those reserved words have special meaning and it is not possible to use them for any activity other than its intended functionality. Example void, return int.

What is the explanation for the dangling pointer in C?

When there is a pointer pointing to a memory address of any variable, but after some time the variable was deleted from the memory location while keeping the pointer pointing to that location is known as a dangling pointer in C.

Describe static function with its usage?

A function, which has a function definition prefixed with a static keyword is defined as a static function. The static function should be called within the same source code.

What is the difference between abs() and fabs() functions?

Both functions are to retrieve absolute value. abs() is for integer values and fabs() is for floating type numbers. Prototype for abs() is under the library file <stdlib.h> and fabs() is under <math.h>.

Describe Wild Pointer in C?

Uninitialized pointers in the C code are known as Wild Pointers. They point to some arbitrary memory location and can cause bad program behavior or program crash.

What is the difference between ++a and a++?

‘++a” is called prefixed increment and the increment will happen first on a variable. ‘a++’ is called postfix increment and the increment happens after the value of a variable used for the operations.

Describe the difference between = and == symbols in C programming?

‘==’ is the comparison operator which is used to compare the value or expression on the left-hand side with the value or expression on the right-hand side.

‘=’ is the assignment operator which is used to assign the value of the right-hand side to the variable on the left-hand side.

What is the explanation for the prototype function in C?

Prototype function is a declaration of a function with the following information to the compiler.

1. Name of the function.
2. The return type of the function.
3. The parameter list of the function.

int sum(int, int); In this example Name of the function is Sum, the return type is the integer data type and it accepts two integer parameters.

What is the explanation for the cyclic nature of data types in C?

Some of the data types in C have special characteristics of nature when a developer assigns a value beyond the range of the data type. There will be no compiler error and the value change according to a cyclic order. This is called cyclic nature and char, int, long, int data types have this property. Further float, double and long double data types do not have this property.

This is called cyclic nature and char, int, long int data types have this property. Further float, double and long double data types do not have this property.

Describe the header file and its usage in C programming?

The file contains the definitions and prototypes of the functions being used in the program are called a header file. It is also known as a library file. Example: The header file contains commands like printf and scanf is the stdio.h library file.

There is a practice in coding to keep some code blocks in comment symbols than delete it when debugging. How this affects when debugging?

This concept is called commenting out and this is the way to isolate some part of the code which scans possible reason for the error. Also, this concept helps to save time because is the code is not the reason for the issue it can simply be removed from comment.

What are the general description for loop statements and available loop types in C?

A statement that allows the execution of a statement or group of statements in a repeated way is defined as a loop.

The following diagram explains a general form of a loop.

There are 4 types of loop statements in C.

1. While loop
2. For Loop
3. Do…While Loop
4. Nested Loop

What is a nested loop?

A loop that runs within another loop is referred to as a nested loop. The first loop is called the Outer Loop and the inside loop is called the Inner Loop. The inner loop executes the number of times defined in an outer loop.

What is the general form of function in C?

The function definition in C contains four main sections.
return_type function_name(parameter list)
{
        Body of the function
}
Return Type: Data type of the return value of the function.
Function Name: The name of the function and it is important to have a meaningful name that describes the activity of the function.
Parameter: The input value for the function that is used to perform the required action.
Function Body: Collection of statements that performs the required action.

What is a pointer on a pointer in C programming language?

A pointer variable that contains the address of another pointer variable is called pointer on a pointer. This concept de-refers twice to point to the data held by a pointer variable.

Int a=5, *x=&a, **y=&x; In this example **y returns the value of the variable a.

What are the valid places to have the keyword “Break”?

The purpose of the Break keyword is to bring the control out of the code block which is executing. It can appear only in looping or switch statements.

What is the behavioral difference when the header file is included in double-quotes (“”) and angular braces (<>)?

When the Header file is included within double quotes (“ “), complier search first in the working directory for the particular header file. If not found, then it searches the file in the include path. But when the Header file is included within angular braces (<>), the compiler only searches in the working directory for the particular header file.

What is a sequential access file?

General program store data into files and retrieve existing data from files. With the sequential access file, such data are saved in a sequential pattern. When retrieving data from such files each data is read one by one until the required information is found.

What is the method to save data in a stack data structure type?

Data is stored in the stack data structure type using the First In Last Out (FILO) mechanism. Only the top of the stack is accessible at a given instance. Storing mechanism is referred to as a PUSH and retrieve is referred to as a POP.

What is the significance of C program algorithms?

The algorithm is created first and it contains step guidelines on how the solution should be. Also, it contains the steps to consider and the required calculations/operations within the program.

Is it possible to use curly brackets ({}) to enclose a single line code in C program?

Yes, it works without any error. Some programmers like to use this to organize the code. But the main purpose of curly brackets is to group several lines of codes.

Describe the modifier in C?

The modifier is a prefix to the basic data type which is used to indicate the modification for storage space allocation to a variable. Example- In a 32-bit processor, storage space for the int data type is 4. When we use it with modifier the storage space change as follows:

Long int: Storage space is 8 bit

Short int: Storage space is 2 bit

What are the modifiers available in the C programming language?

There are 5 modifiers available in the C programming language as follows:
Short
Long
Signed
Unsigned
Long long

Is that possible to store 32768 in an int data type variable?

Int data type is only capable of storing value between -32768 to 32767. To store 32768 a modifier needs to use with the int data type. Long Int can use and also if there are no negative values, unsigned int is also possible to use.

Is there any possibility to create a customized header file with the C programming language?

Yes, it is possible and easy to create a new header file. Create a file with function prototypes that are used inside the program. Include the file in the ‘#include’ section from its name.

Describe dynamic data structure in the C programming language?

The dynamic data structure is more efficient in memory. The memory access occurs as needed by the program.

Is that possible to add pointers to each other?

There is no possibility to add pointers together. Since the pointer contains address details there is no way to retrieve the value from this operation.

What is indirection?

If you have defined a pointer to a variable or any memory object, there is no direct reference. But when we declare a variable, it has a direct reference to the value. This is called indirect reference. But when we declare a variable, it has a direct reference to the value.

What are the ways to a null pointer that can be used in the C programming language?

Null pointers are possible to use in three ways.
As an error value.
As a sentinel value.
To terminate indirection in the recursive data structure.

What is the explanation for modular programming?

The process of dividing the main program into executable subsection is called module programming. This concept promotes reusability.

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