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TOPICS TO DISCUSS :FUNCTIONS

TYPES OF FUNCTIONSHEADER FILES

PRESENTED BY:AVISHEK MAJUMDAR(837837)GUNJAN AGARWAL(856587)SATYAPRIYA DEY(856624)

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FUNCTIONC Functions are a set of instructions enclosed by “{ }” which performs specific

operations in a C program.

The advantage of using function is to avoid rewriting of of same code and logic.

There are 3 aspects in each C function:

1.Function declaration or prototype

2.Function call

3.Function definition

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#include<stdio.h>float sum ( float x,float y ); // Function declarationint main( ) // main function { float a,b, s; printf ( "\n Enter two numbers” \n"); scanf ( "%f%f", &a,&b ); s=add(a,b); // Function call printf ( "\nThe Sum of two numbers are %f ",s ); } float sum ( float x,float y ) // Function definition { float p; p = x +y; return p; }

EXAMPLE OF FUNCTIONS

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CONTINUED....CALL BY VALUE The value of the variable is passed to

the function.float square ( float x ); int main( ){ float m, n; printf ( "\n Enter a number for

finding the square \n"); scanf ( "%f", &m ); n = square ( m ); printf ( "\n Square of the given

number %f is %f",m,n ); } float square ( float x ) { float p; p = x * x; return p; }

CALL BY REFERENCEThe address of the variable is passed

to the functionvoid swap (int *x, int *y); int main( ) { int num1 = 5, num2 = 6; swap ( &num1, &num2 ); // function

call printf ( "\n After swapping the values

are %d and %d”, num1, num2 ); } void swap ( int *x, int *y ) { int temp; temp = *x; *x = *y;*y = temp;}

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TYPES OF FUNCTIONTYPES OF FUNCTION

Functions are basically of two types:1.Library Functions

2.User Defined Function

LIBRARY FUNCTION:Library functions are the in-built functions in C

Programming Language.

Examples: main(), printf(), scanf()

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TYPES OF User Defined FUNCTIONTYPES OF User Defined FUNCTION

Function can basically be categorized as:Function with arguments and return type-declaration:float calculate_area(int);definition:float calculate_area(int radius){float area_of_circle;area_of_circle=3.14*radius*radius;return area_of_circle;}Function with arguments and without return type-declaration:void calculate_area(int);definition:void calculate_area(int radius){float area_of_circle;area_of_circle=3.14*radius*radius;printf(“Area of the circle of radius-%d is-%d”,radius,area);}

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Function without arguments and without return type-declaration:void calculate_area();definition:void calculate_area(){float area_of_circle,radius;printf(“Enter the value of radius”);scanf(“%f”,&radius);area_of_circle=3.14*radius*radius;printf(“Area of the circle of radius-%d is-%d”,radius,area);}

Function without arguments and with return type-declaration:int calculate_area();definition:int calculate_area(){float area_of_circle,radius;printf(“Enter the value of radius”);scanf(“%f”,&radius);area_of_circle=3.14*radius*radius;return area_of_circle;}

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printf() :formatted writescanf() :formatted readgets() :read stringputs() :write string

#include <stdio.h> int main(){ int number; printf("Enter an integer\n"); scanf("%d", &number); printf("Integer that you have entered is %d\n", number); return 0;}

Header file is a file,containing C declarations and macro definitions to be shared between several source files. To use the header files in a program we have to include it,with the C preprocessing directive ‘#include’ . A header file have extension .h .

stdio.h

What is Header files..What is Header files..

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Header files serve two purposes.

System header files declare the interfaces to parts of the operating system. I have to include them in program to supply the definitions and declarations.

My own header files contain declarations for interfaces between the source files of programs. Each time I have a group of related declarations and macro definitions all or most of which are needed in several different source files, it is a good idea to create a header file for them.

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Header files used in C..stdio.h: Include all the input output function

stdlib.h: include all the library function

math.h : Include all the mathematical functions

string.h: Include all string manipulation functions

ctype.h: Include all character manipulating functions

conio.h: Include all console input output functions

stddef.h: Standard type definitions

Time.h: Contains the C date and time operations

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