Introduction to Functions in C

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Questions and Answers

What is a function in C?

A function in C is a group of statements that together perform a specific well-defined task.

Which of these is NOT a type of function in C?

Recursive Functions

Inline Functions (correct)

Standard/Pre-Defined/Library Functions

User-Defined Functions

What are the main components of a user-defined function in C?

The main components of a user-defined function in C are the function prototype (declaration), the function calling (calling function), and the function definition (or called function).

Pre-defined functions in C can be modified by the user.

False Signup and view all the answers

What is the advantage of using user-defined functions in C?

All of the above Signup and view all the answers

In C, what is the purpose of a function prototype?

A function prototype in C acts as a declaration for a function, informing the compiler about the return type, function name, and the number and type of arguments the function expects. Signup and view all the answers

What does the term "actual parameter" refer to in the context of C functions?

An actual parameter in C is the value or variable that is passed to a function when it is called. It represents the information that is being given to the function to work with. Signup and view all the answers

What distinguishes a function that doesn't return a value in C?

In C, a function that doesn't return a value is explicitly declared with the keyword "void" as its return type. This indicates to the compiler that the function does not produce a result that needs to be passed back to the calling function. Signup and view all the answers

What is a recursive function in C?

A function that calls itself. Signup and view all the answers

What's the primary reason for choosing "call by reference" over "call by value"?

Call by reference allows modification of original variables passed to the function. Signup and view all the answers

How does "call by value" work in C?

In call by value, a copy of the value of the actual parameter is made and passed to the function. So, if you modify the formal parameter within the function, it doesn't affect the original value in the calling function. Signup and view all the answers

How does "call by reference" work in C?

In call by reference, the address of the actual parameter is passed to the function. This means that the formal parameter in the function points to the same memory location as the original variable. So, any changes to the formal parameter directly affect the actual parameter. Signup and view all the answers

Study Notes

Introduction to Functions

Programs can become large and complex, making debugging difficult.
Dividing programs into smaller, independent subprograms (functions) simplifies the process.
C language supports this structuring using functions.
Functions are building blocks of C programs.
A function groups statements to perform a specific task.

Definition of a Function

A function is a block of one or more statements that perform a specific task.
A function is a small, independent units of a program.
Two main types of functions:
- Standard/Predefined/Library Functions.
- User Defined Functions.

Predefined Functions

Predefined functions are pre-written sets of statements in C header files.
Their purpose is limited(e.g., printing out results)
Users of these functions don't need to know the internal workings.
Programs need to include the correct header file to use the function.

User Defined Functions in C

User-defined functions are created according to user requirements.
Users can adjust function definitions to their needs.
Understanding the function's internal workings is important for defining functions well.
User-defined functions reduce code size and increase programs' reusability.
Reusable code simplifies debugging and helps structure large projects.
Functions increase program readability.

Parts of a User Defined Function

Function Prototype/Declaration
Function Calling/Call
Function Definition/Called Function

Function Prototype/Declaration

A function prototype tells the compiler about the function's details.
It includes the function's name, return type, and argument types and names.
It's declared before the main function (local declaration) or outside of the main function (global declaration).
Example: int sum(int, int);

Function Calling/Call

Function calls use the function's name and pass data (arguments).
Called functions get the data from the calling functions.
Called functions process data according to instructions and may return values.

Function Definition/Called Function

It's the actual function containing code to perform the stated task.
It takes arguments as specified in the prototype.
It might return a result using the return keyword.

Working of a Function

Arguments of calling functions are called actual parameters.
Arguments of called functions are called formal parameters.
The argument list is enclosed in parenthesis () and separated by a comma ,. By default user defined functions return an integer value.
By using the void keyword functions can return no value.

Types of User Defined Functions

Function without return type and without arguments
Function without return type and with arguments
Function with return type and without arguments
Function with return type and with arguments

1. Function without return type and without arguments

No data is passed to the function.
No value is returned to the calling function.
The function performs operations independently.
Example: Print/display statements(not returning values)

2. Function without return type and with arguments

Arguments passed to the function but no value returned..
The function operates on the incoming arguments.

3. Function with return type and without arguments

The function returns a value to the calling function.
No values received as arguments.

4. Function with return type and with arguments

The function receives arguments from the calling function.
The function returns a value to the calling function.

Recursion

A function calling itself is recursion.
This method makes solving some problems simpler. e.g. calculating factorials.

Call by Value

A copy of the actual parameter is passed to the formal parameter.
Changes inside the function don't affect the original values.
Distinct memory space.

Call by Reference

The address of the actual parameter is passed.
Changes inside the function directly modify the original values.
Same memory space.

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Description

This quiz covers the essential concepts of functions in the C programming language. It explores the definition, types of functions, and the distinction between predefined and user-defined functions. Understand how functions can simplify program structure and enhance code manageability.