Functions in C

Function Call

Function definition   

Function declaration

#include<stdio.h>

#include<conio.h>

void main()

{

int addnum(int,int);

int sum,a,b;

printf(“Enter two number:”);

scanf(“%d%d”,&a,&b);

sum=addnum(a,b);

printf(“The sum of %d and %d is %d”,a,b,sum);

getch();

}

int addnum(num1,num2)

{

int tot;

tot=num1+num2;

return(tot);

}

#include<stdio.h>

#include<conio.h>

void main()

{

char lower,upper;

clrscr();

printf(“Enter a lower-case character:”);

scanf(“%c”,&lower);

upper=lower_to_upper(lower);

printf(“The upper case equivalent is %c\n\n”,upper);

getch();

}

char lower_to_upper(char c1)

{

char c2;

c2=(c1>=’a’ && c1<=’z’)?(c1-32):c1;

return(c2);

}

#include<stdio.h>

#include<conio.h>

void main()

{

char lower,upper;

clrscr();

printf(“Enter a upper-case character:”);

scanf(“%c”,&upper);

lower=upper_to_lower(upper);

printf(“The lower case equivalent is %c\n\n”,lower);

getch();

}

char upper_to_lower(char c1)

{

char c2;

c2=(c1>=’A’ && c1<=’Z’)?(c1+32):c1;

return(c2);

}

Function Reference

#include<stdio.h>

#include<conio.h>

void main()

{

int maximum(int,int);

int a,b,c,d;

clrscr();

printf(“\n a=”);

scanf(“%d”,&a);

printf(“\n b=”);

scanf(“%d”,&b);

printf(“\n c=”);

scanf(“%d”,&c);

d=maximum(a,b);

printf(“\n Maximum=%d”,maximum(c,d));

getch();

}

int maximum(int x,int y)

{

int z;        

z=(x>=y)?x:y;

return(z);

}

Function without argument and with return value:

#include<stdio.h>

#include<conio.h>

void main()

{

int add();

int r;

clrscr();

r=add();

printf(“%d”,r);

printf(“%d”,add());

getch();

}

int add()

{

int a,b,c;

printf(“\n Enter two numbers:”);

scanf(“%d%d”,&a,&b);

c=a+b;

return ( c );

}

Function with argument and with return value

#include<stdio.h>

#include<conio.h>

void main()

{

int add(int,int);

int a,b,r;

clrscr();

printf(“\n Enter two numbers:”);

scanf(“%d%d”,&a,&b);

r=add(a,b);

printf(“%d”,r);

getch();

}

int add(int x, int y)

{

int c;

c=x+y;

return ( c );

}