This document provides an overview of functions in C programming. It defines a function as a block of code that performs a specific task and can be called multiple times. The key points covered are: - Functions allow programs to be divided into smaller, reusable tasks. - Functions may return data to the calling function and accept arguments to operate on. - Function prototypes provide the compiler with function signatures before they are defined. - Function definitions implement the code bodies with the same return type and arguments as the prototype. - Functions can be called by value, where arguments are copied, or by reference, where addresses are passed.

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Functions in C

3. CONTENTS
• What is a function??
• Advantages
• How the function works?
• Function prototypes
• Function defnitions

4. A large program in c can be divided to many subprogram
The subprogram is called as a function
Basically a job of function is to do something
 C program contain at least one function which is main().

5. Classification
Functions
User defined
function
Library
function
-printf()
-scanf()
-pow()
-ceil()
- main()

6. Program can be divided into a smaller, simpler task.
Allowing the code to be called many times
Easier to read and update
 Easier Error handling
Code reusability

7. C program doesn't execute the statement in function until the
function is called.
When function is called the program can send the function
information in the form of one or more argument.
When the function is used it is referred to as the called function
Functions often use data that is passed to them from the calling
function
Data is passed from the calling function to a called function by
specifying the variables in a argument list.
Argument list cannot be used to send data. Its only copy
data/value/variable that pass from the calling function.

8. Provides the compiler with the description of functions that will be used
later in the program
Its define the function before it been used/called
Function prototypes need to be written at the beginning of the program.
The function prototype must have :
A return type indicating the variable that the function will be return
Syntax for Function Prototype
• return-type function_name( arg-type name-1,...,arg-type name-n);
Function Prototype Examples
 double squared( double number );
 void print_report( int report_number );
 int get_menu_choice( void);

9.  It is the actual function that contains the code that will be execute.
 Should be identical to the function prototype.
Syntax of Function Definition
• return-type function_name( arg-1,...,arg-n) ----Function header
{
declarations;
statements;
return(expression);
}
Function Body

10. • Function Definition Examples
float conversion (float celsius)
{
float fahrenheit;
fahrenheit = celcius*33.8
return fahrenheit;
}
• Can be any of C’s data type: int , float etc…

11. Call by value
• In call by value mechanism, the called function
creates a new set of variables in stack and
copies the values of the arguments into them.

12. Call by reference
In call by reference mechanism, instead of
passing values to the function being called,
references/pointers to the original variables
are passed.

13. Thankyou…

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