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 k3y 10Mar2012 01:24

For Loops [basic]

Hey guys,
I just learned the basics of FOR loops and felt maybe I should share for fellow n00bs out there. A FOR loop can in many cases replace a WHILE loop. This tutorial will show you the relationship between the WHILE loop and the FOR loop, as well as an exercise that I found to be very helpful in learning how to utilize them.
Syntax of a WHILE loop:

Code:

```i = 1; // initializer while (i <= 10) // condition {     cout << i << " ";     i++; // increment }```
Now in a FOR loop

Syntax of a FOR loop:
Code:

```for (i=1; i <= 10; i++) //initializer; condition; increment   cout << i << " ";```
Now as you can see the FOR loop is much more condensed then the WHILE loop, and saves some headache. Now it's time for an example code (test a number for primeness):
Code:

```#include <iostream> #include <math.h> using namespace std; int main() {     int n;     bool is_prime = true; // boolean (assumes true)     cout << "Enter a number and press ENTER: ";     cin >> n;     for (int i = 2; i <= sqrt(n); i++)     {         if (n % i == 0) // if the remainder of n divided by i is zero         is_prime = false; // then n is not prime     } // Print result     if (is_prime)     {         cout << "Number is prime." << endl;     }     else     {         cout << "Number is not prime." << endl;     }     return 0; }```
Here are a few good exercises to get yourself familiar with WHILE and FOR.
Exercises:
- optimize this program
- find the correct place to put a break statement
- make the same program using a WHILE loop

Hope this can help someone

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