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C++ For Loop

C++ For Loop

In order to iterate a part of the program numerous times, the For loop in C++ is used. It is generally recommended to use the For loop instead of while or do-while loop when the number of iterations are certain/predefined. The programmers can check conditions, increment/decrement value and initialize the variable in C++ by using the For loop.

Here is the syntax of the For loop in C++

 for(initialization; condition; incr/decr)
 {    
//code to be executed    
}    

Here is an example of the For loop(Print 1 to 10)

#include <iostream>  
using namespace std;  
int main() 
{  
	 for(int i=1;i<=10;i++)
	 {      
		cout<<i<<"\n";      
	 }       
}   
Output :
1
2
3
4
5
6
7
8
9
10

Here is another example of the For loop(Print all even number from 1 to 100)

#include <iostream>  
using namespace std;  
int main() 
{  
	 for(int i=1;i<=100;i++)
	 {      
		if(i%2==0)
		{
		cout<<i<<" ";      
		}   
	}	 
}   
Output :
2 4 6 8 10 12........... 100

Here is another example of the For loop(Print the sum of even and odd number from 1 to 100)

#include <iostream>  
using namespace std;  
int main() 
{  
int even=0;
int odd=0;
	 for(int i=1;i<=100;i++)
	 {      
		if(i%2==0)
		{
		even=even+i;      
		}   
		else
		{
		odd=odd+i;
		}
	}
cout<<"Sum of even="<<even<<"\n";
cout<<"Sum of odd="<<odd;	
}   
Output :
Sum of even=2550
Sum of odd=2500

C++ Nested For Loop

A For loop can be used inside another For loop and it is called as the Nested For loop in C++ programming. Whenever the outer loop that is created gets executed once then the inner loop gets executed completely. For instance if the inner and outer loop are executed for 3 times then the inner loop will be executed 3 times for each outer loop that will be 9 times in total.

Here is an example of the nested For loop in the C++ programming:

#include <iostream>  
using namespace std;  
int main () 
{  
        for(int i=1;i<=2;i++)
		{      
             for(int j=1;j<=2;j++)
			 {      
            cout<<i<<" "<<j<<"\n";      
			}     
        }  
    }    
Output :
1 1
1 2
2 1
2 2

Here is another example of the nested For loop to print Triangle:

#include <iostream>  
using namespace std;  
int main () 
{  
        for(int i=1;i<=3;i++)
		{      
             for(int j=1;j<=i;j++)
			 {      
            cout<<" * ";      
			}
		cout<<"\n";
        }  
    }    
Output :
*
* *
* * *

Here is another example of the nested For loop

#include <iostream>  
using namespace std;  
int main () 
{  
        for(int i=1;i<=3;i++)
		{      
             for(int j=1;j<=3;j++)
			 {      
            cout<<i;      
			}
		cout<<"\n";
        }  
    }    
Output :
111
222
333

Here is another example of the nested For loop

#include <iostream>  
using namespace std;  
int main () 
{  
        for(int i=1;i<=3;i++)
		{      
             for(int j=1;j<=i;j++)
			 {      
            cout<<j;      
			}
		cout<<"\n";
        }  
    }    
Output :
1
12
123

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