> ## Documentation Index
> Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt
> Use this file to discover all available pages before exploring further.
# PHP While Loop
The `while` loop in PHP is a pre-test control flow statement that repeatedly executes a block of code as long as a specified boolean condition evaluates to `true`. Because the condition is evaluated before each iteration, the loop body will execute zero times if the initial condition evaluates to `false`.
## Syntax
PHP supports two syntactical structures for the `while` loop: the standard curly-brace syntax and the alternative colon-based syntax (commonly used in templating).
**Standard Syntax:**
```php theme={"dark"}
while (expression) {
// Statements to execute
}
```
**Alternative Syntax:**
```php theme={"dark"}
while (expression):
// Statements to execute
endwhile;
```
## Execution Mechanics
1. **Expression Evaluation:** At the start of each iteration, PHP evaluates the `expression`.
2. **Type Casting:** PHP automatically casts the result of the `expression` to a boolean. Values considered "truthy" (e.g., non-zero integers, non-empty strings, populated arrays) evaluate to `true`. Values considered "falsy" (e.g., `0`, `0.0`, `""`, `null`, `[]`, `false`) evaluate to `false`.
3. **Execution:** If the expression is `true`, the statements within the block are executed sequentially.
4. **Re-evaluation:** Once the block completes, execution returns to step 1. This cycle continues until the expression evaluates to `false`.
## State Mutation
To prevent an infinite loop, the code block within the `while` loop must eventually mutate the state of the variables evaluated in the `expression`.
```php theme={"dark"}
$iteration = 0;
while ($iteration < 3) {
echo $iteration;
$iteration++; // Mutates state to eventually yield a false condition
}
// Output: 012
```
## Loop Control Statements
PHP provides specific keywords to alter the standard execution flow of a `while` loop from within its block:
* **`break`**: Immediately terminates the execution of the `while` loop. Program control resumes at the next statement following the loop block. You can pass an optional integer argument (e.g., `break 2;`) to break out of multiple nested loops.
* **`continue`**: Halts the current iteration, skipping any remaining statements in the block, and immediately jumps back to the expression evaluation to begin the next iteration. Like `break`, it accepts an optional integer argument to skip iterations of nested loops.
```php theme={"dark"}
$i = 0;
while ($i < 5) {
$i++;
if ($i === 2) {
continue; // Skips the echo for $i = 2
}
if ($i === 4) {
break; // Terminates the loop entirely
}
echo $i;
}
// Output: 13
```
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