C++ Functions
Advantage of
functions
1) Code Reuse
2) Code optimization
3)Memory execution
fast
Declaration of a
function
syntax
return_type function_name(data_type parameter...)
{
//code to be executed
}
Function with
Parameters
#include <iostream.h>
#include<conio.h>
void display(int n1, float n2) {
//function definition
cout <<
"The int number is " << n1;
cout <<
"The double number is " << n2;
}
void main() {
int num1
= 5;
double
num2 = 5.5;
display(num1,
num2); // function call
getch();
}
Output
The int number is 5
The double number is 5.5
Add Two
Numbers
#include <iostream.h>
#include<conio.h>
int add(int a, int b) {
return (a + b);
}
void main() {
int sum;
sum = add(100,
78);
cout <<
"sum = " << sum << endl;
getch();
}
Output
sum = 178
Function
Overloading
Function name same
argument different
#include <iostream.h>
#include<conio.h>
void display(int var1, double var2) {
cout <<
"Integer number: " << var1;
cout <<
" and double number: " << var2 << endl;
}
void display(double var) {
cout <<
"Double number: " << var << endl;
}
void display(int var) {
cout <<
"Integer number: " << var << endl;
}
void main() {
int a = 5;
double b = 5.5;
display(a);
display(b);
display(a, b);
getch();
}
Output
Integer number: 5
Float number: 5.5
Integer number: 5 and double number: 5.5
Inline function
It improves the execution time and speed of the
program
#include <iostream.h>
#include<conio.h>
inline int add(int a, int b)
{
return(a+b);
}
void main()
{
cout<<"Addition of 'a' and 'b' is:"<<add(2,3);
getch();
}
output
Addition of 'a' and 'b' is:
5
Recursion
A function that calls itself is known as
a recursive function.
// Factorial of n = 1*2*3*...*n
#include
<iostream.h>
#include<conio.h>
int factorial(int);
void main() {
int
n, result;
cout
<< "Enter a non-negative number: \n";
cin
>> n;
result
= factorial(n);
cout
<< "Factorial of " << n << " = " <<
result;
getch();
}
int factorial(int n) {
if
(n > 1) {
return
n * factorial(n - 1);
}
else {
return
1;
}
}
Output
Enter a non-negative number: 4
Factorial of 4 = 24
Function
with Default Argument
#include<iostream.h>
#include<conio.h>
int sum(int x=10,int y=20,int z=30);
void main()
{
cout<<"sum()="<<sum()<<endl;
cout<<"sum(15)="<<sum(15)<<endl;
cout<<"sum(15,25)="<<sum(15,25)<<endl;
cout<<"sum(15,25,35)="<<sum(15,25,35)<<endl;
getch();
}
int sum(int x,int y,int z)
{
return(x+y+z);
}
output
sum()=60
sum(15)=65
sum(15,25)=70
sum(15,25,35)=75
Function with Const Argument
#include<iostream.h>
#include<conio.h>
void main()
{
float cmtot(const int cm);
int cm;
cout<<"Enter the length in
cm";
cin>>cm;
cout<<"Meter:"<<cmtot(cm)<<endl;
}
float cmtot(const int cm)
{
return (float)cm/100;
}
output
Enter
the length in cm:125
Meter: 1.25
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