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3. Func tions Definition :
The function is sub program or set of instructions written to do a particular task. We have already used functions like printf() , scanf() , strlen() etc. Every C program can be thought of as a collection of these functions.
There are basically two needs of function:
1. Writing functions avoids rewriting the same code again and again.
2. Using function it becomes easier to write a program.
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4. Example : Function #include<stdio.h> void Hello();
//1. function declaration
int main() {
Hello();
printf(“I a return 0; }
void Hell {
printf(“Hello World }
Output:
Hello World I am back
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5. Types of function call
Function call is of two types
1. Call by value
2. Call by reference
Call by value: when we call function by passing normal values (or variable), the function call is called as call by value. We have already seen an example of this type above.
Call by reference: when we call function by passing reference of variable or values, the function call is called as call by reference.
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6. Cal l by v alue #include<stdio.h> int add (int , int);
//1. function declaration
int main() {
int y
y=Add(5,6);
// 2. function call (5,6) are actual argument
printf(“addition = %d” , y);
return 0; }
int add (int x, int y) {
// 3. function definition x &y are formal argument
int result;
result=x+y;
return result; }
output:
addition =11

7. Return Values #include<stdio.h> int add (int , int);
//1. function declaration
int main() {
int y=Add(5,6);
// 2. function call (5,6) are actual argument
printf(“addition = %d” , y); return 0; }
int add (int x, int y) {
// 3. function definition
return (x+y);
// return (expression) }
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8. Recursion main(); //main() is called again in its own function body
Definition :
In C, it is possible for the functions to call themselves. A function is called
‘recursive’ if a statement within the body of a function calls the same function.
Output:
#include<stdio.h> #include<conio.h>
Hello
Hello
int main() {
Hello
Hello
printf(“\nHello”)͖
main(); //main() is called again in its own function body
getch();
return 0;
Note: run indefinitely as no }
break condition
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9. St r u c t u re
A simple variable can hold a single element of any data type.
Array allows user to store multiplevalues of same data type.
Structure allows user to store multiple values of different data type.
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10. Example : Structure member #include<stdio.h> int main()
struct keyword
structure name {
st {
int pages ;
member
//structure declaration
flo
} ;
terminating semicolon
struct book b1;
// sets aside space in memory
printf ( "\n Enter no. of pages & price of book\n" ) ;
scanf ( " %d %f", &b1.pages, &b1.price ) ;
//Accessing member of structure
printf ( "\n You entered : " ) ;
printf ( "\n %c %f %d", b1.pages, b1.price) ; }
//Accessing member of structure
Output:
Enter no. of pages & price of book
You entered

11. End of chapter