Iteration

Iteration is simply the repetition of a block of code in a program. In many cases, we need a control variable to implement iteration. Alternatively, we can repeatedly execute a block of code until a certain stopping criterion is met.

Generally you can implement iteration using for, while or do-while loop constructs (in some programming languages we have the alternate repeat construct). Let's look at an example pseudo-code, where we print numbers from 1 to 5 using a control variable i.

As the values of i change in the loop, the numbers 1, 2, 3, 4, 5 are printed. The loop is executed as long as the condition i <= 5 holds true.

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let i = 1; // Initial value of control variable

// Repeat the next block till condition i <= 5 is true

while (i <= 5) {

  console.log(i); // Print i

  i = i + 1; // Increment i by 1

}