Definition

A for loop is a control structure used in programming to repeat a block of code a specific number of times. It typically consists of three parts:

1. Initialization: Sets a starting value.
2. Condition: The loop continues as long as this is true.
3. Update: Changes the loop variable after each iteration.

The general syntax in many languages (like C, Java, or Python) is:

• C/Java:

``
for (initialization; condition; update) {
// code block
}
`

• Python:

`
for variable in range(start, stop, step):

code block

`

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Worked Example

Example: Print the numbers from 1 to 5.

C/Java-style

`c
for (int i = 1; i <= 5; i++) { printf("%dn", i); } `

Python-style

`python
for i in range(1, 6):
print(i)
``

Explanation:

• Initialization: $i = 1$
• Condition: $i \leq 5$
• Update: $i$ increases by $1$ each time The loop prints $1, 2, 3, 4, 5$.

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Key Takeaways

• A for loop repeats code a set number of times, controlled by a loop variable.
• The three main parts are initialization, condition, and update.
• Syntax varies by language, but the logic is the same: start, continue while true, update.