What is wrong in this statement? scanf(“%d”,whatnumber);
An ampersand & symbol must be placed before the variable name whatnumber. Placing & means whatever integer value is entered by the user is stored at the “address” of the variable name. This is a common mistake for programmers, often leading to logical errors.
How do you generate random numbers in C?
Random numbers are generated in C using the rand() command. For example: anyNum = rand() will generate any integer number beginning from 0, assuming that anyNum is a variable of type integer.
What could possibly be the problem if a valid function name such as tolower() is being reported by the C compiler as undefined?
The most probable reason behind this error is that the header file for that function was not indicated at the top of the program. Header files contain the definition and prototype for functions and commands used in a C program. In the case of “tolower()”, the code “#include <ctype.h>” must be present at the beginning of the program.
What are comments and how do you insert it in a C program?
Comments are a great way to put some remarks or description in a program. It can serves as a reminder on what the program is all about, or a description on why a certain code or function was placed there in the first place. Comments begin with /* and ended by */ characters. Comments can be a single line, or can even span several lines. It can be placed anywhere in the program.
What is debugging?
Debugging is the process of identifying errors within a program. During program compilation, errors that are found will stop the program from executing completely. At this state, the programmer would look into the possible portions where the error occurred. Debugging ensures the removal of errors, and plays an important role in ensuring that the expected program output is met.
What are binary trees?
Binary trees are actually an extension of the concept of linked lists. A binary tree has two pointers, a left one and a right one. Each side can further branch to form additional nodes, which each node having two pointers as well.
Not all reserved words are written in lowercase. TRUE or FALSE?
FALSE. All reserved words must be written in lowercase; otherwise the C compiler would interpret this as unidentified and invalid.
What is the difference between the expression “++a” and “a++”?
In the first expression, the increment would happen first on variable a, and the resulting value will be the one to be used. This is also known as a prefix increment. In the second expression, the current value of variable a would the one to be used in an operation, before the value of a itself is incremented. This is also known as postfix increment.
What would happen to X in this expression: X += 15; (assuming the value of X is 5)
X +=15 is a short method of writing X = X + 15, so if the initial value of X is 5, then 5 + 15 = 20.
In C language, the variables NAME, name, and Name are all the same. TRUE or FALSE?
FALSE. C language is a case sensitive language. Therefore, NAME, name and Name are three uniquely different variables.
What is an endless loop?
An endless loop can mean two things. One is that it was designed to loop continuously until the condition within the loop is met, after which a break function would cause the program to step out of the loop. Another idea of an endless loop is when an incorrect loop condition was written, causing the loop to run erroneously forever. Endless loops are oftentimes referred to as infinite loops.
What is a program flowchart and how does it help in writing a program?
A flowchart provides a visual representation of the step by step procedure towards solving a given problem. Flowcharts are made of symbols, with each symbol in the form of different shapes. Each shape may represent a particular entity within the entire program structure, such as a process, a condition, or even an input/output phase.
What is wrong with this program statement? void = 10;
The word void is a reserved word in C language. You cannot use reserved words as a user-defined variable.
Is this program statement valid? INT = 10.50;
Assuming that INT is a variable of type float, this statement is valid. One may think that INT is a reserved word and must not be used for other purposes. However, recall that reserved words are express in lowercase, so the C compiler will not interpret this as a reserved word.
Write a program to print factorial of given number without using recursion?
#include<stdio.h>
#include<conio.h>
void main(){
int i,fact=1,number;
clrscr();
printf("Enter a number: ");
scanf("%d",&number);
for(i=1;i<=number;i++){
fact=fact*i;
}
printf("Factorial of %d is: %d",number,fact);
getch();
}
Write a program to print factorial of given number using recursion?
#include<stdio.h>
#include<conio.h>
long factorial(int n) // function to calculate the factorial of a given number.
{
if (n == 0)
return 1;
else
return(n * factorial(n-1)); //calling the function recursively.
}
void main()
{
int number; //declaration of variables.
long fact;
clrscr();
printf("Enter a number: ");
scanf("%d", &number);
fact = factorial(number); //calling a function.
printf("Factorial of %d is %ld\n", number, fact);
getch(); //It reads a character from the keyword.
}
What are actual arguments?
When you create and use functions that need to perform an action on some given values, you need to pass these given values to that function. The values that are being passed into the called function are referred to as actual arguments.
What is a newline escape sequence?
A newline escape sequence is represented by the \n character. This is used to insert a new line when displaying data in the output screen. More spaces can be added by inserting more \n characters. For example, \n\n would insert two spaces. A newline escape sequence can be placed before the actual output expression or after.
What is output redirection?
It is the process of transferring data to an alternative output source other than the display screen. Output redirection allows a program to have its output saved to a file. For example, if you have a program named COMPUTE, typing this on the command line as COMPUTE >DATA can accept input from the user, perform certain computations, then have the output redirected to a file named DATA, instead of showing it on the screen.
What are run-time errors?
These are errors that occur while the program is being executed. One common instance wherein run-time errors can happen is when you are trying to divide a number by zero. When run-time errors occur, program execution will pause, showing which program line caused the error.
What are structure types in C?
Structure types are primarily used to store records. A record is made up of related fields. This makes it easier to organize a group of related data.
What does the characters “r” and “w” mean when writing programs that will make use of files?
“r” means “read” and will open a file as input wherein data is to be retrieved. “w” means “write”, and will open a file for output. Previous data that was stored on that file will be erased.
What is the difference between text files and binary files?
Text files contain data that can easily be understood by humans. It includes letters, numbers and other characters. On the other hand, binary files contain 1s and 0s that only computers can interpret.
is it possible to create your own header files?
Yes, it is possible to create a customized header file. Just include in it the function prototypes that you want to use in your program, and use the #include directive followed by the name of your header file.
What is dynamic data structure?
Dynamic data structure provides a means for storing data more efficiently into memory. Using dynamic memory allocation, your program will access memory spaces as needed. This is in contrast to static data structure, wherein the programmer has to indicate a fix number of memory space to be used in the program.
What are the different data types in C?
The basic data types are int, char, and float. Int is used to declare variables that will be storing integer values. Float is used to store real numbers. Char can store individual character values.
What is the general form of a C program?
A C program begins with the preprocessor directives, in which the programmer would specify which header file and what constants (if any) to be used. This is followed by the main function heading. Within the main function lies the variable declaration and program statement.
What is the difference between functions abs() and fabs()?
These 2 functions basically perform the same action, which is to get the absolute value of the given value. Abs() is used for integer values, while fabs() is used for floating type numbers. Also, the prototype for abs() is under <stdlib.h>, while fabs() is under <math.h>.
What are formal parameters?
In using functions in a C program, formal parameters contain the values that were passed by the calling function. The values are substituted in these formal parameters and used in whatever operations as indicated within the main body of the called function.
What are control structures?
Control structures take charge at which instructions are to be performed in a program. This means that program flow may not necessarily move from one statement to the next one, but rather some alternative portions may need to be pass into or bypassed from, depending on the outcome of the conditional statements.
Write a simple code fragment that will check if a number is positive or negative.
If (num>=0)
printf("number is positive");
else
printf ("number is negative");
When is a “switch” statement preferable over an “if” statement?
The switch statement is best used when dealing with selections based on a single variable or expression. However, switch statements can only evaluate integer and character data types.
What are global variables and how do you declare them?
Global variables are variables that can be accessed and manipulated anywhere in the program. To make a variable global, place the variable declaration on the upper portion of the program, just after the preprocessor directives section.
What are enumerated types?
Enumerated types allow the programmer to use more meaningful words as values to a variable. Each item in the enumerated type variable is actually associated with a numeric code. For example, one can create an enumerated type variable named DAYS whose values are Monday, Tuesday… Sunday.
What does the function toupper() do?
It is used to convert any letter to its upper case mode. Toupper() function prototype is declared in <ctype.h>. Note that this function will only convert a single character, and not an entire string.
Is it possible to have a function as a parameter in another function?
Yes, that is allowed in C programming. You just need to include the entire function prototype into the parameter field of the other function where it is to be used.
What are multidimensional arrays?
Multidimensional arrays are capable of storing data in a two or more dimensional structure. For example, you can use a 2 dimensional array to store the current position of pieces in a chess game, or position of players in a tic-tac-toe program.
Which function in C can be used to append a string to another string?
The strcat function. It takes two parameters, the source string and the string value to be appended to the source string.
What is the difference between functions getch() and getche()?
Both functions will accept a character input value from the user. When using getch(), the key that was pressed will not appear on the screen, and is automatically captured and assigned to a variable. When using getche(), the key that was pressed by the user will appear on the screen, while at the same time being assigned to a variable.
Dothese two program statements perform the same output? 1) scanf(“%c”, &letter); 2) letter=getchar()
Yes, they both do the exact same thing, which is to accept the next key pressed by the user and assign it to variable named letter.
What is the advantage of a random access file?
If the amount of data stored in a file is fairly large, the use of random access will allow you to search through it quicker. If it had been a sequential access file, you would have to go through one record at a time until you reach the target data. A random access file lets you jump directly to the target address where data is located.
An ampersand & symbol must be placed before the variable name whatnumber. Placing & means whatever integer value is entered by the user is stored at the “address” of the variable name. This is a common mistake for programmers, often leading to logical errors.
How do you generate random numbers in C?
Random numbers are generated in C using the rand() command. For example: anyNum = rand() will generate any integer number beginning from 0, assuming that anyNum is a variable of type integer.
What could possibly be the problem if a valid function name such as tolower() is being reported by the C compiler as undefined?
The most probable reason behind this error is that the header file for that function was not indicated at the top of the program. Header files contain the definition and prototype for functions and commands used in a C program. In the case of “tolower()”, the code “#include <ctype.h>” must be present at the beginning of the program.
What are comments and how do you insert it in a C program?
Comments are a great way to put some remarks or description in a program. It can serves as a reminder on what the program is all about, or a description on why a certain code or function was placed there in the first place. Comments begin with /* and ended by */ characters. Comments can be a single line, or can even span several lines. It can be placed anywhere in the program.
What is debugging?
Debugging is the process of identifying errors within a program. During program compilation, errors that are found will stop the program from executing completely. At this state, the programmer would look into the possible portions where the error occurred. Debugging ensures the removal of errors, and plays an important role in ensuring that the expected program output is met.
What are binary trees?
Binary trees are actually an extension of the concept of linked lists. A binary tree has two pointers, a left one and a right one. Each side can further branch to form additional nodes, which each node having two pointers as well.
Not all reserved words are written in lowercase. TRUE or FALSE?
FALSE. All reserved words must be written in lowercase; otherwise the C compiler would interpret this as unidentified and invalid.
What is the difference between the expression “++a” and “a++”?
In the first expression, the increment would happen first on variable a, and the resulting value will be the one to be used. This is also known as a prefix increment. In the second expression, the current value of variable a would the one to be used in an operation, before the value of a itself is incremented. This is also known as postfix increment.
 |
| Naver Frequently Asked C Language Interview Questions Answers |
What would happen to X in this expression: X += 15; (assuming the value of X is 5)
X +=15 is a short method of writing X = X + 15, so if the initial value of X is 5, then 5 + 15 = 20.
In C language, the variables NAME, name, and Name are all the same. TRUE or FALSE?
FALSE. C language is a case sensitive language. Therefore, NAME, name and Name are three uniquely different variables.
What is an endless loop?
An endless loop can mean two things. One is that it was designed to loop continuously until the condition within the loop is met, after which a break function would cause the program to step out of the loop. Another idea of an endless loop is when an incorrect loop condition was written, causing the loop to run erroneously forever. Endless loops are oftentimes referred to as infinite loops.
What is a program flowchart and how does it help in writing a program?
A flowchart provides a visual representation of the step by step procedure towards solving a given problem. Flowcharts are made of symbols, with each symbol in the form of different shapes. Each shape may represent a particular entity within the entire program structure, such as a process, a condition, or even an input/output phase.
What is wrong with this program statement? void = 10;
The word void is a reserved word in C language. You cannot use reserved words as a user-defined variable.
Is this program statement valid? INT = 10.50;
Assuming that INT is a variable of type float, this statement is valid. One may think that INT is a reserved word and must not be used for other purposes. However, recall that reserved words are express in lowercase, so the C compiler will not interpret this as a reserved word.
Write a program to print factorial of given number without using recursion?
#include<stdio.h>
#include<conio.h>
void main(){
int i,fact=1,number;
clrscr();
printf("Enter a number: ");
scanf("%d",&number);
for(i=1;i<=number;i++){
fact=fact*i;
}
printf("Factorial of %d is: %d",number,fact);
getch();
}
Write a program to print factorial of given number using recursion?
#include<stdio.h>
#include<conio.h>
long factorial(int n) // function to calculate the factorial of a given number.
{
if (n == 0)
return 1;
else
return(n * factorial(n-1)); //calling the function recursively.
}
void main()
{
int number; //declaration of variables.
long fact;
clrscr();
printf("Enter a number: ");
scanf("%d", &number);
fact = factorial(number); //calling a function.
printf("Factorial of %d is %ld\n", number, fact);
getch(); //It reads a character from the keyword.
}
What are actual arguments?
When you create and use functions that need to perform an action on some given values, you need to pass these given values to that function. The values that are being passed into the called function are referred to as actual arguments.
What is a newline escape sequence?
A newline escape sequence is represented by the \n character. This is used to insert a new line when displaying data in the output screen. More spaces can be added by inserting more \n characters. For example, \n\n would insert two spaces. A newline escape sequence can be placed before the actual output expression or after.
What is output redirection?
It is the process of transferring data to an alternative output source other than the display screen. Output redirection allows a program to have its output saved to a file. For example, if you have a program named COMPUTE, typing this on the command line as COMPUTE >DATA can accept input from the user, perform certain computations, then have the output redirected to a file named DATA, instead of showing it on the screen.
What are run-time errors?
These are errors that occur while the program is being executed. One common instance wherein run-time errors can happen is when you are trying to divide a number by zero. When run-time errors occur, program execution will pause, showing which program line caused the error.
What are structure types in C?
Structure types are primarily used to store records. A record is made up of related fields. This makes it easier to organize a group of related data.
What does the characters “r” and “w” mean when writing programs that will make use of files?
“r” means “read” and will open a file as input wherein data is to be retrieved. “w” means “write”, and will open a file for output. Previous data that was stored on that file will be erased.
What is the difference between text files and binary files?
Text files contain data that can easily be understood by humans. It includes letters, numbers and other characters. On the other hand, binary files contain 1s and 0s that only computers can interpret.
is it possible to create your own header files?
Yes, it is possible to create a customized header file. Just include in it the function prototypes that you want to use in your program, and use the #include directive followed by the name of your header file.
What is dynamic data structure?
Dynamic data structure provides a means for storing data more efficiently into memory. Using dynamic memory allocation, your program will access memory spaces as needed. This is in contrast to static data structure, wherein the programmer has to indicate a fix number of memory space to be used in the program.
What are the different data types in C?
The basic data types are int, char, and float. Int is used to declare variables that will be storing integer values. Float is used to store real numbers. Char can store individual character values.
What is the general form of a C program?
A C program begins with the preprocessor directives, in which the programmer would specify which header file and what constants (if any) to be used. This is followed by the main function heading. Within the main function lies the variable declaration and program statement.
What is the difference between functions abs() and fabs()?
These 2 functions basically perform the same action, which is to get the absolute value of the given value. Abs() is used for integer values, while fabs() is used for floating type numbers. Also, the prototype for abs() is under <stdlib.h>, while fabs() is under <math.h>.
What are formal parameters?
In using functions in a C program, formal parameters contain the values that were passed by the calling function. The values are substituted in these formal parameters and used in whatever operations as indicated within the main body of the called function.
What are control structures?
Control structures take charge at which instructions are to be performed in a program. This means that program flow may not necessarily move from one statement to the next one, but rather some alternative portions may need to be pass into or bypassed from, depending on the outcome of the conditional statements.
Write a simple code fragment that will check if a number is positive or negative.
If (num>=0)
printf("number is positive");
else
printf ("number is negative");
When is a “switch” statement preferable over an “if” statement?
The switch statement is best used when dealing with selections based on a single variable or expression. However, switch statements can only evaluate integer and character data types.
What are global variables and how do you declare them?
Global variables are variables that can be accessed and manipulated anywhere in the program. To make a variable global, place the variable declaration on the upper portion of the program, just after the preprocessor directives section.
What are enumerated types?
Enumerated types allow the programmer to use more meaningful words as values to a variable. Each item in the enumerated type variable is actually associated with a numeric code. For example, one can create an enumerated type variable named DAYS whose values are Monday, Tuesday… Sunday.
What does the function toupper() do?
It is used to convert any letter to its upper case mode. Toupper() function prototype is declared in <ctype.h>. Note that this function will only convert a single character, and not an entire string.
Is it possible to have a function as a parameter in another function?
Yes, that is allowed in C programming. You just need to include the entire function prototype into the parameter field of the other function where it is to be used.
What are multidimensional arrays?
Multidimensional arrays are capable of storing data in a two or more dimensional structure. For example, you can use a 2 dimensional array to store the current position of pieces in a chess game, or position of players in a tic-tac-toe program.
Which function in C can be used to append a string to another string?
The strcat function. It takes two parameters, the source string and the string value to be appended to the source string.
What is the difference between functions getch() and getche()?
Both functions will accept a character input value from the user. When using getch(), the key that was pressed will not appear on the screen, and is automatically captured and assigned to a variable. When using getche(), the key that was pressed by the user will appear on the screen, while at the same time being assigned to a variable.
Dothese two program statements perform the same output? 1) scanf(“%c”, &letter); 2) letter=getchar()
Yes, they both do the exact same thing, which is to accept the next key pressed by the user and assign it to variable named letter.
What is the advantage of a random access file?
If the amount of data stored in a file is fairly large, the use of random access will allow you to search through it quicker. If it had been a sequential access file, you would have to go through one record at a time until you reach the target data. A random access file lets you jump directly to the target address where data is located.