C Programming Interview Questions Answers Part-I

88) What is difference between compilers from interpreters?

Compilers and interpreters often deal with how program codes are executed. Interpreters execute program codes one line at a time, while compilers take the program as a whole and convert it into object code, before executing it. The key difference here is that in the case of interpreters, a program may encounter syntax errors in the middle of execution, and will stop from there. On the other hand, compilers check the syntax of the entire program and will only proceed to execution when no syntax errors are found.

89) How do you declare a variable that will hold string values?

The char keyword can only hold 1 character value at a time. By creating an array of characters, you can store string values in it. Example: “char MyName[50]; ” declares a string variable named MyName that can hold a maximum of 50 characters.

90) Can the curly brackets { } be used to enclose a single line of code?

While curly brackets are mainly used to group several lines of codes, it will still work without error if you used it for a single line. Some programmers prefer this method as a way of organizing codes to make it look clearer, especially in conditional statements.

91) What are header files and what are its uses in C programming?

Header files are also known as library files. They contain two essential things: the definitions and prototypes of functions being used in a program. Simply put, commands that you use in C programming are actually functions that are defined from within each header files. Each header file contains a set of functions. For example: stdio.h is a header file that contains definition and prototypes of commands like printf and scanf.

92) What are variables and it what way is it different from constants?

Variables and constants may at first look similar in a sense that both are identifiers made up of one or more characters (letters, numbers and a few allowable symbols). Both will also hold a particular value.  Values held by a variable can be altered throughout the program, and can be used in most operations and computations. Constants are given values at one time only, placed at the beginning of a program. This value is not altered in the program. For example, you can assigned a constant named PI and give it a value 3.1415 .  You can then use it as PI in the program, instead of having to write 3.1415 each time you need it.

93) How do you access the values within an array?

Arrays contain a number of elements, depending on the size we gave it during variable declaration. Each element is assigned a number from 0 to (number of elements-1). To assign or retrieve the value of a particular element, refer to the element number. For example: if you have a declaration that says “int scores[5];”, then you have 5 accessible elements, namely: scores[0], scores[1], scores[2], scores[3] and scores[4].

94) Can two or more operators such as n and t be combined in a single line of program code?

Yes, it’s perfectly valid to combine operators, especially if the need arises. For example: you can have a code like ”printf (“Hellonn’World’”) ” to output the text “Hello” on the first line and “World” enclosed in single quotes to appear on the next two lines.

95) Why is it that not all header files are declared in every C program?

The choice of declaring a header file at the top of each C program would depend on what commands/functions you will be using in that program. Since each header file contains different function definitions and prototype, you would be using only those header files that would contain the functions you will need. Declaring all header files in every program would only increase the overall file size and load of the program, and is not considered a good programming style.

96) When is the “void” keyword used in a function?

When declaring functions, you will decide whether that function would be returning a value or not. If that function will not return a value, such as when the purpose of a function is to display some outputs on the screen, then “void” is to be placed at the leftmost part of the function header. When a return value is expected after the function execution, the data type of the return value is placed instead of “void”.

97) What are compound statements?

A compound statement (also called a “block”) typically appears as the body of another statement, such as the if statement, for statement, while statement, etc

A Compound statement consists of several individual statements enclosed within a pair of braces { }. The individual statements may themselves be expression statements, compound statements or control statements. Unlike expression statements, a compound statement does not end with a semicolon.

{
    pi=3.14;
    area=pi*radius*radius;
}

A typical Compound statement is given below.

98) What is the advantage of an array over individual variables?

When storing multiple related data, it is a good idea to use arrays. This is because arrays are named using only 1 word followed by an element number. For example: to store the 10 test results of 1 student, one can use 10 different variable names (grade1, grade2, grade3… grade10). With arrays, only 1 name is used, the rest are accessible through the index name (grade[0], grade[1], grade[2]… grade[9]).

99) Write a loop statement that will show the following output:
1
12
123
1234
12345

for (a=1; a<=5; i++)
{
 for (b=1; b<=a; b++) 
 printf("%d",b); 
 printf("\n");
}

100) What does the format %10.2 mean when included in a printf statement?
This format is used for two things: to set the number of spaces allotted for the output number and to set the number of decimal places. The number before the decimal point is for the allotted space, in this case it would allot 10 spaces for the output number. If the number of space occupied by the output number is less than 10, addition space characters will be inserted before the actual output number. The number after the decimal point sets the number of decimal places, in this case, it’s 2 decimal spaces.

I hope you have found this post useful. Normally in any interview, questions starts with basic concept of subject and later they continue further discussion on advance topics to check whether candidate have fully understood or not. This is why C Programming Interview Questions Answers Part-I focus more on basic fundamentals to open up interview. In next post will explore more on Advance C Programming related questions. I recommend you to check C Programming Interview Questions and Answers Part-II. Thank You and Good Luck!!!