UP Board Solutions Class 10 Computer Science Chapter 9 Functions and Sub Routines

Functions And Sub-Routines Long Answer Type Questions (8 Marks)

Question 1. What do you mean by function in ‘C'? Or What is the library function in 'C'? Explain.
Answer: Introduction: Sometimes, to perform a particular task in a program, you may have to write another program which may be a very cumbersome process. Functions are very useful to read, write, debug and modify complex programs. They can also be easily incorporated in the main program. In 'C' language, main() itself is a function that means the main function is invoking the other functions to perform various tasks. There are two types of functions:
1. Built-in functions/Library Function.
2. User-defined functions.
1. Built-in Functions/Library Functions: These are the pre-defined routines that are included as an integral part of the language. Each function is accessed simply by stating its name, followed by whatever information must be supplied to the function, enclosed in parentheses (A numeric quantity or a string that is passed to a function in this manner is called an argument). Library functions are also called standard functions or elementary functions. These functions provide a quick and easy way to evaluate many mathematical functions and to carry out certain logical operations. There are several library functions in 'C' Language. Basic Library functions are of two types:
• String Functions: String functions operate on strings, e.g., strlen (), strrev()
• Numeric Functions: Numeric functions operate on numeric values, e.g., ABS(), EXP(), SIN(), cos().
2. User-defined Functions: This feature allows you to define functions within a program, which you can call whenever you need them. While running the program (FUNC) statement can save space as well time, as a complex calculation can be defined with a short name and called up by its name where needed.
In simple words: Functions in 'C' are blocks of code designed to perform specific tasks, making programs organized and reusable. They can be pre-defined (library functions) or created by the user (user-defined functions).

🎯 Exam Tip: Understanding the distinction and application of built-in versus user-defined functions is crucial for scoring well on 'C' programming questions.

Question 2. What are user-defined functions? Explain with example.
Answer: User-defined Functions: This feature allows you to define functions within a program, which you can call whenever you need them. While running the program (FUNC) statement can save space as well as time, as a complex calculation can be defined with a short name and called up by its name where needed. Defining a Function
main()
{
printf ("I am in function main \n");
India();
printf ("I am finally back in function main \n”);
}
India()
{
printf ("I am in India \n”);
Delhi();
printf ("I am back in India \n");
}
Delhi()
{
printf ("I am in Delhi \n”);
Bombay();
}
Bombay()
{
printf ("I am in Bombay");
}
Output: I am in function main I am in India I am in Delhi I am in Bombay I am back in India I am finally back in function main
In simple words: User-defined functions are custom blocks of code created by a programmer to perform specific tasks. They help in breaking down complex programs into smaller, manageable, and reusable parts, saving time and space.

🎯 Exam Tip: When explaining user-defined functions, always include a clear, simple code example to illustrate declaration, definition, and calling, as this demonstrates practical understanding.

Question 3. WAP to demonstrate a function declaration, function calling and function definition.
Answer: Program:
#include
void main (void)
{
void display (void); /* function declaration */ display (); /* function calling */
}
void display (void)/* function definition */
{
printf ("this is a test program \n");
printf ("for demonstrating a function call \n”);
printf ("in C \n”);
}
Output: this is a test program for demonstrating a function call in C
In simple words: This program illustrates how to declare a function (telling the compiler about it), call it (using it in main), and define it (providing its actual code).

🎯 Exam Tip: For programming questions, clearly separate the function declaration, calling, and definition in your example code for maximum clarity and scoring.

Question 4. Explain Return statement with example.
Answer: Return Statement: The keyword return is used to terminate function and return a value to its caller. The return statement may also be used to exit a function without returning a value. The return statement may or may not include an expression. Example Program:
#include
void main (void)
{
float max (float, float, float);
float a, b, c maximum;
printf ("Enter three numbers\n");
scanf ("%d %d %d", &a, &b &c);
maximum = max (a, b, c);
printf("maximum = %d, maximum);
}
float max (float x, float y, float z)
{
if (x > y)
{
if (x > z)
return (x);
}
else
{
if (y > z)
return (z);
else
return (z);
}
}
Output: Enter three numbers 2 4 8 maximum = 8
In simple words: The `return` statement in a function stops its execution and sends a value back to where the function was called. It can be used with or without a value.

🎯 Exam Tip: Emphasize that `return` signals the end of function execution and the potential transfer of a result to the caller; a clear code example showcasing value return is vital.

Functions And Sub-Routines Short Answer Type Questions (4 Marks)

Question 1. What is the status of 'C' language? Why is 'C' language so popular in the software world? Explain. Or Why is 'C' a very popular language? Explain with suitable example.
Answer: Programming Language is a set of instructions and keywords which help a user to communicate with the computer. The 'C' programming language was developed by Dennis Ritchie in Bell Telephone Laboratories, in the early 1970s. Ken Thompson and his team supported him in developing this language. In the late seventies, ‘C' began to replace the more familiar languages of that time like PL/I, ALGOL, etc. In less than a decade of its introduction, 'C' has become a language of choice for software professionals because it is reliable, simple and easy to use. The UNIX operating system was written in 'C' language.
One of the most interesting things about the 'C' language is that its compiler is written in 'C'. 'C' language is considered as a middle-level language since it was designed to have both a relatively good programming efficiency and a relatively good machine efficiency. It is a bridge between low level and high-level languages.
• 'C' language possesses features of both low level and high-level languages.
• It provides the facility to do programming with easy approaches.
• It provides the facility to do programming at register level which leads to fast processing.
• It consists of simple English like commands, which are easy to understand.
• The programs written in 'C' language are 100 per cent efficient and are also machine-independent and portable.
• A 'C' program is easier to write and does not vary much from computer to computer.
In simple words: 'C' is a middle-level programming language developed by Dennis Ritchie, popular due to its efficiency, portability, and ability to handle both low-level hardware interactions and high-level programming concepts. It's widely used because it's reliable, simple, and easy to use.

🎯 Exam Tip: Focus on 'C' as a middle-level language and its key features like efficiency, portability, and its role in system programming (like UNIX) to address its popularity.

Question 2. Define ABS function with example.
Answer: ABS(X): This function gives the absolute value of X. The absolute value of a constant is always independent of its sign ie., it is always positive. For example:
#include
#include
void main()
{
int a = -20, b = -20.23, c = 18.5
printf ("%d %d %d", abs(a), abs(b), abs(c));}
Output: 20 20.23 18.5
In simple words: The ABS() function returns the absolute (non-negative) value of a number. For example, the absolute value of -20 is 20, and of 18.5 is 18.5.

🎯 Exam Tip: Remember to state that the ABS function always returns a positive value, regardless of the input's original sign. A simple code example reinforces understanding.

Question 3. Define SQR function with example.
Answer: SQR(X): function returns the square root of its argument which should never be negative. For example:
#include
#include
void main()
{
int a = 4, b;
b = sqr(a);
printf ("%d", b);
}
Output: 2
In simple words: The SQR() function calculates and returns the square root of a given number. The input argument for this function must be a non-negative value.

🎯 Exam Tip: Highlight the prerequisite that the argument for the SQR function must not be negative to avoid errors. An example showing a perfect square is ideal.

Functions And Sub-Routines Very Short Answer Type Questions (2 Marks)

Question 1. What is argument?
Answer: The value we pass in a function at the time of its calling is known as an argument.
In simple words: An argument is a piece of data, a value or variable, that you provide to a function when you call it, so the function can use that information to perform its task.

🎯 Exam Tip: Define arguments precisely as values passed *to* a function *during* its call, differentiating them from parameters defined *in* the function signature.

Question 2. What is Numeric function?
Answer: The numeric function works on numeric values.
In simple words: A numeric function is a type of function that takes numbers as input and produces a numerical output, performing mathematical operations.

🎯 Exam Tip: A concise definition stating that numeric functions operate solely on numerical data types is sufficient for full marks.

Question 3. What is the use of EXP function?
Answer: EXP function is used to return the exponential value of the argument.
In simple words: The EXP() function calculates 'e' raised to the power of its argument, where 'e' is Euler's number (approximately 2.71828).

🎯 Exam Tip: Explicitly mention that EXP calculates the exponential function (e^x) for the given argument to ensure a complete answer.

Question 4. What is the other name of the pre-defined function?
Answer: The pre-defined function is also known as built-in function.
In simple words: Pre-defined functions are also called built-in functions because they are already part of the programming language's library, ready for immediate use.

🎯 Exam Tip: Simply stating "built-in function" or "library function" as an alternative name is enough for this direct question.

Question 5. Who developed 'C' language?
Answer: Dennis Ritchie and Ken Thompson.
In simple words: The 'C' programming language was primarily developed by Dennis Ritchie, with contributions from Ken Thompson, at Bell Labs.

🎯 Exam Tip: A straightforward answer naming Dennis Ritchie is essential, with Ken Thompson as a valuable addition for historical accuracy.

Question 6. A loop within a loop is known as ........
Answer: Nested loop.
In simple words: A loop placed inside another loop is known as a nested loop. This structure is used when you need to repeat a sequence of operations for each iteration of an outer loop.

🎯 Exam Tip: The key term "Nested loop" is the direct answer. Briefly explaining its structure (loop inside a loop) confirms understanding.

Functions And Sub-Routines Objective Type Questions (1 Marks)

Question 1. Functions which are compiled into object modules are known as (a) Library functions (b) Recursive functions (c) User-defined functions (d) None of these.
Answer: (a) Library functions
In simple words: Library functions are pre-compiled functions available in the programming language's standard library that can be linked into your program.

🎯 Exam Tip: Remember that library functions are pre-compiled and readily available for use, unlike user-defined or recursive functions.

Question 2. The default return type of a user-defined function is: (a) void (b) float (c) char (d) int
Answer: (d) int
In simple words: If you don't explicitly specify a return type for a function in 'C', the compiler assumes it will return an integer (`int`) by default.

🎯 Exam Tip: It's important to recall that in C, `int` is the default return type if no other type is specified for a function.

Question 3. A user-defined function can be called: (a) One time (b) Two times (c) Three times (d) More than three times.
Answer: (d) More than three times.
In simple words: A user-defined function can be called any number of times within a program, making code reusable and efficient.

🎯 Exam Tip: A core benefit of functions is reusability; they can be called repeatedly as needed throughout a program, not just a fixed number of times.

Question 4. Language used to design web pages is: (a) C++ (b) BASIC (c) HTML (d) JAVA.
Answer: (c) HTML
In simple words: HTML (HyperText Markup Language) is the standard language used to create the structure and content of web pages.

🎯 Exam Tip: HTML is fundamental for web page structure; distinguish it from programming languages like C++ or Java, which provide logic and interactivity.

Question 5. The value passed at the time of calling a function is known as: (a) Variables (b) Constants (c) Arguments (d) None of these.
Answer: (c) Arguments
In simple words: When you call a function, the specific values or variables you provide to it are referred to as arguments.

🎯 Exam Tip: Differentiate "arguments" (values passed during function call) from "parameters" (variables listed in the function definition) for precise terminology.

Question 6. Which of the following is short-cut for 'Save' operation? (a) Control + P (b) Control + S (c) Control + N (d) Control + F
Answer: (b) Control + S
In simple words: In most applications and operating systems, "Control + S" (or Command + S on Mac) is the universal keyboard shortcut used to save the current document or work.

🎯 Exam Tip: This is a general computer literacy question; "Control + S" is the standard shortcut for saving across most applications.