C++ - Chapter 4 - Loops

Introduction

Suppose you are tasked with writing a program that needs to iteratively calculate a value. This could be computing a summation, multiplication tables, compound interest, or an infinite number of other items. You could write a single line of code for every calculation that needs to be made, or you implement the calculation in a loop.

There are three types of loops in C++: the for loop, the while loop, and the do/while loop. Each type has it's own advantages.

The codes below will illustrate the use of each of the types of loops.

Definitions (in layman's terms)

For Loop A loop that continues until an incrementation variable has reached a predefined value.

While Loop A loop that is only executed and continued when (a) specified condition(s) is(are) true.

Do/While Loop A loop that is executed at least once and continues only if (a) specified condition(s) is(are) true.

Code:

#include <iostream>

using namespace std;

int main (void)
{
	int x, y;

	for (x = 0; x < 5; x++)
	{
		cout<<"I have looped: "<<x<<" times."<<endl;
	}

	return 0;
}

Output

I have looped: 0 times.
I have looped: 1 times.
I have looped: 2 times.
I have looped: 3 times.
I have looped: 4 times.

Breakdown

A for loop is initialized by the statement: for (x = 0; x < 5; x++). The syntax of this is:
for (initial_value; value_inequality; value_increment)

The statements within the for loop are bracketed, although this is not a requirement for a single statement. In the example above, we could have typed:

for (x = 0; x < 5; x++)
	cout<<"I have looped: "<<x<<" times."<<endl;

< Back - Working with Text

Index

Next - Loops >