C++ For Loop - Learn C++ , C++ Tutorial , C++ programming
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- Loops are used in programming to repeat a specific block of code. In this, you will learn to create a for loop in C++ programming (with examples).
learn c++ tutorials - for loop Example
- Loops are used in programming to repeat a specific block until some end condition is met.
- There are three type of loops in C++ programming:
- for loop
- while loop
- do...while loop
- In this, you are going to learn for loop only
C++ for Loop Syntax
- A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times.
for(initializationStatement; testExpression; updateStatement) {
// codes
}
- where, only testExpression is mandatory.
How for loop works?
- The initialization statement is executed only once at the beginning.
- Then, the test expression is evaluated.
- If the test expression is false, for loop is terminated. But if the test expression is true, codes inside body of for loop is executed and update expression is updated.
- Again, the test expression is evaluated and this process repeats until the test expression is false.
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Flowchart of for Loop in C++
Example 1: C++ for Loop
// C++ Program to find factorial of a number
// Factorial on n = 1*2*3*...*n
#include <iostream>
using namespace std;
int main()
{
int i, n, factorial = 1;
cout << "Enter a positive integer: ";
cin >> n;
for (i = 1; i <= n; ++i) {
factorial *= i; // factorial = factorial * i;
}
cout<< "Factorial of "<<n<<" = "<<factorial;
return 0;
}Learn C++ , C++ Tutorial , C++ programming - C++ Language -Cplusplus
Output
Enter a positive integer: 5
Factorial of 5 = 120
- In the program, user is asked to enter a positive integer which is stored in variable n(suppose user entered 5). Here is the working of for loop:
- Initially, i is equal to 1, test expression is true, factorial becomes 1.
- i is updated to 2, test expression is true, factorial becomes 2.
- i is updated to 3, test expression is true, factorial becomes 6.
- i is updated to 4, test expression is true, factorial becomes 24.
- i is updated to 5, test expression is true, factorial becomes 120.
- i is updated to 6, test expression is false, for loop is terminated.
- In the above program, variable i is not used outside of the for loop. In such cases, it is better to declare the variable in for loop (at initialization statement).
#include <iostream>
using namespace std;
int main()
{
int n, factorial = 1;
cout << "Enter a positive integer: ";
cin >> n;
for (int i = 1; i <= n; ++i) {
factorial *= i; // factorial = factorial * i;
}
cout<< "Factorial of "<<n<<" = "<<factorial;
return 0;
}