This simulation allows you to explore two main experiments:

1. Factorial Calculation using Loops
2. Pyramid Pattern using Nested Loops

You can switch between these two modes at any time using the Switch to Nested Loop or Switch to Simple Loop button. Each experiment can be performed in two ways:

• Start with the default mode (Simple Loop for factorial, Nested Loop for pyramid)
• Or switch to the other mode using the switch button

Experiment 1: Factorial Calculation (Simple Loop)

1. By default, the simulation opens in the Simple Loop mode.
2. Select the loop type (for, while, or do-while) from the dropdown menu.
3. Enter the number P whose factorial you want to calculate. P must be a whole number from 0 to 12, because 13! is too large to store in a C int.
4. Click Start to begin the simulation.
5. The code for the selected loop will be displayed, and the Next button will be enabled.
6. Click Next repeatedly to execute the code step by step. The line shown in red is the line that has just been executed, and the local variables p, i and fact show their values after that line. A short note below the variables explains the step, e.g. check i>=1 → 0>=1 is false.
7. The working of each multiplication (e.g. fact = 1 * 3 = 3) is listed in the output box, and the value printed by the program is shown as Output.
8. When the program ends, the message Execution finished. Press Start to run again. appears. You can then choose another loop type or value and click Start again.
9. To try the pyramid pattern experiment, click Switch to Nested Loop.

Experiment 2: Pyramid Pattern (Nested Loop)

1. Click Switch to Nested Loop to open the nested loop simulation (or start here if already in this mode).
2. Enter the height of the pyramid, a whole number from 1 to 7.
3. Click Start to begin the simulation.
4. The code for the nested loop will be displayed, and the Next button will be enabled.
5. Click Next repeatedly to execute the code step by step. The line shown in red is the line that has just been executed, the local variables height, i, j and k are updated, and the pyramid is drawn in the output box one character at a time. Spaces are shown as _ so that they are visible.
6. When the program ends, the message Execution finished. Press Start to run again. appears.
7. To return to factorial calculation, click Switch to Simple Loop.

Things to observe

• Only executable lines are stepped through. Lines containing only { or } are skipped, because nothing is executed there.
• Uninitialised variables are shown as ? until they are given a value (for example, p after int p; and before scanf).
• Loop conditions are checked each time the loop header (for(...), while(...), or }while(...);) is highlighted. In a do-while loop, the body runs once before the condition is checked for the first time.
• Scope of i in the for loop: i is declared inside the for statement, so it exists only while the loop runs. After the loop ends, i is shown as out of scope. In the while and do-while programs, i is declared before the loop, so its final value (0) is still shown.
• P = 0: the condition p==0 is true, so the program prints 1 and returns immediately without entering the loop.

Note for Mobile Users:

This simulation is optimized for desktop computers with larger screens and mouse interaction. If you access this experiment on a mobile device, please rotate your device to landscape mode for the best experience. Some features may be limited or harder to use on small screens.

Manual

This simulation demonstrates:

• How different looping constructs (for, while, do-while) can be used to calculate the factorial of a non-negative integer.
• How nested loops can be used to generate a pyramid pattern of any given height.