CBSE Class 12 Computer Science User Defined Functions Assignment

Question. In C, the program execution starts from?
Answer: main() function

Question. A function that perform no action?
Answer: dummy function

Question. The default return data type in function is?
Answer: int

Question. The parameter passing mechanism used in C is?
Answer: Call by Value and call by Reference

Question. The function main() is?
Answer: A user define function

Question. How many main() functions can be defined in a C program?
Answer: one

Question. ____________ function is used to calculate the power of a number.
Answer: pow()

Question. The functions are predefined and supplied along with the compiler?
Answer: Built-in functions

Question. Function declaration ends with a _?
Answer: ; (semicolon)

Question. A function that does not return anything has return type?
Answer: void

Question. Functions are commonly divided into __ types.
Answer: two

State Whether True or False?

Question. Is it compulsory to have one return statement in a function?
Answer: False

Question. Is it possible that a function can contain more than one return statement?
Answer: True

Question. Can we pass a constant through a function?
Answer: True

Question. Function can return more then one values using return statement?
Answer: False

Question. To get back from a function, we must use return statement?
Answer: True

Exercise Questions

Question. Distinguish between arguments and parameters?
Answer: These are variables used in function. These are the optional part of the function. Their existence depends on the requirement of the user. It means there may be zero or more arguments. These arguments are of two types:
• Arguments (Actual parameters)
• Parameters (Formal parameters)
Arguments: Variables used in a function call are called arguments. These are written within the parentheses ( ) after the function name in the function call. They are also called actual parameters.
Parameters: Variables used in the function definition are called parameters. They are also called formal parameters. They receive values form the calling function. Parameters must be written within the parentheses ( ) after the function name in function definition.

Question. What is the need of function declaration?
Answer: Function declaration is also called Function Prototyping. It is different from function definition. It does npot have any body. It is terminated with semicolon (;). Function declaration provides the information to the compiler about the type of function, its name and arguments. When we call a function to use it, compiler verifies the function call with its declaration. If function declaration does not found, compiler will display an error message.

Question. How does a function definition differ from function declaration?
Answer: Function declaration is also called Function Prototyping. It is different from function definition. It does npot have any body. It is terminated with semicolon (;). Function declaration provides the information to the compiler about the type of function, its name and arguments. When we call a function to use it, compiler verifies the function call with its declaration. If function declaration does not found, compiler will display an error message.
Function Definition defines the working of the function. In the definition of a function, we define the type, name, arguments and body of the function.

Question. What role does the return statement play?
Answer: Return is a keyword. It is used in the definition of functions. This keyword is used in those functions which return a value to their calling function. Return statement must be the last statement in the body of the function. For
example:
int sum(int a, int b)
{
int c=a+b;
return c;
}
In the above example, the function sum() returns the value of c to its calling functions with the help of return statement.

Question. When will the execution of the function terminates?
Answer: Function is the logical grouping of statements. Functions are used to solve a complex problem by dividing it into smaller parts. A function once defined can be used many times. When a function is called, it starts its execution. This execution goes on till the end of the body of the function. When function completes its execution, program control is returned to the calling function.

Question. Explain the advantages or uses of function?
Answer: Using functions have a number of advantages. The main advantages of using a function are:
• It becomes easy to solve a complex program by dividing it into small functions.
• It becomes easy to debug the program.
• It is easy to maintain and modify a function.
• It allows the reusability of code. A function can be called any number of times but defined only once.
• Small functions are self-documenting.
• It allows the programmer to build a library of the commonly used functions.
• It facilitates top-down modular programming approach.

Other Important Questions

Question. What are functions? Write their types.
Answer: A function is a subprogram. It is also called a Routine or Procedure. It is a logical grouping of statements in a program. Functions are used to solve a complex problem by dividing it into smaller parts. A function once defined can be used many times. In every executable programs, there must be a main() function in the program. Program execution starts from this main function. In other words, we can say that main function act as a entry point of execution on the program. Types of Functions:
Functions can be classified mainly into two categories:

1. Library or Built-in functions
2. User defined functions

Question. What are Library Functions?
Answer: Those functions, which are in-built or pre-defined in the C language, are called standard or library functions. All these functions are organized in header files (also called library files). To use any library function, we must include the corresponding header file (in which it is defined) in our program. For example: clrscr( ), printf(), scanf(), sqrt(), strcpy() etc. are the predefined functions. The input output functions scanf( ) and printf( ) are defined in the stdio.h header file. So, we have to include this file in our program if we want to use these functions. Similarly, string functions strlen( ), strcpy( ), strcat( ), strcmp( ), strupr( ), strlwr( ) etc. are defined in the string.h header file. So, we must include string.h header file to use these string functions in our program.

Question. What are User Defined Functions?
Answer: Those functions, which are defined by the user, are called user defined functions. User can define his own functions to fulfil his requirements. The function main() is an example of user defined function. Its body is defined by user.

Question. What are Storage Classes?
Answer: Storage classes are used to define the scope, life and location of a variable in the program. In C, four storage classes are used to define scope, life and location of variable. These are:
1. Automatic Variables 2. Register Variables 3. Static Variables 4.External Variables