For loop executes a series of statements multiple times and shortens the code that manages the loop variable. This means, that a for loop is a type of repetition control structure that allows us to write a loop that is executed a certain number of times. The loop allows us to perform an n number of steps in a single line.
In the previous tutorial, we learned about the basic concept of the loop in C++.
for (initialization expr; test expr; update expr)
{
// body of the loop
// statements we want to execute
}
For example
for(int i = 0; i < n; i++){
}
A loop variable is used to control the loop in a for loop
. First, assign a value to this loop variable, then determine whether it is less than or greater than the counter value. The loop body is executed and the loop variable is updated if the statement is true. Steps are repeated until the exit condition is reached.
for loop
. For example, i<= 10;
#include <iostream>
using namespace std;
int main()
{
for (int i = 1; i <= 10; i++)
{
cout << "Learn eTutorials\n";
}
return 0;
}
Output:
Learn eTutorials Learn eTutorials Learn eTutorials Learn eTutorials Learn eTutorials
We can check how this program works
Iteration | Variable | i <= 5 | Action |
---|---|---|---|
1st | i = 1 |
true |
Learn eTutorials is printed and i is increased to 2 . |
2nd | i = 2 |
true |
Learn eTutorials is printed and i is increased to 3 . |
3rd | i = 3 |
true |
Learn eTutorials is printed and i is increased to 4 . |
4th | i = 4 |
true |
Learn eTutorials is printed and i is increased to 5 . |
5th | i = 5 |
true |
Learn eTutorials is printed and i is increased to 6 . |
6th | i = 6 |
false |
The loop is terminated |
#include <iostream>
using namespace std;
int main() {
for (int i = 1; i <= 5; ++i) {
cout << i << "\n";
}
return 0;
}
Output:
1 2 3 4 5
In the above example, we are printing the numbers from 1 to 5. For that, we first have initialized a variable i
with value “1” and in the condition parameter we check the condition i <= 5
and if the condition is true the block of the for loop will execute, and after the execution, the increment/decrement parameter will be executed and in that the value of the variable i
is increment and the loop will continue till the condition i <= 10
becomes false.
Iteration | Variable | i <= 5 | Action |
---|---|---|---|
1st | i = 1 |
true |
1 is printed and i is increased to 2 . |
2nd | i = 2 |
true |
2 is printed and i is increased to 3 . |
3rd | i = 3 |
true |
3 is printed and i is increased to 4 . |
4th | i = 4 |
true |
4 is printed and i is increased to 5 . |
5th | i = 5 |
true |
5 is printed and i is increased to 6 . |
6th | i = 6 |
false |
The loop is terminated |