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78 lines
2.0 KiB
Markdown
78 lines
2.0 KiB
Markdown
+++
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title = "Loops"
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description = "Increase your repetitions"
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tags = ["php", "loop", "foreach", "for"]
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slug = "loops"
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previous = "conditionals.html"
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next = "arrays.html"
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+++
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A loop tells PHP to run a block of code more than once.
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A classic loop is a while loop.
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A `while` loop will continue to run the block of code as long as the value in parentheses is true.
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```php
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<?php
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$num = 5;
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while ($num > 0) {
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echo "While loop $num\n";
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--$num;
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}
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```
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A `do while` loop is similar to a `while` loop except it always runs at least
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one iteration. In a classic `while` loop, no iterations may be executed if
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the value in parentheses is false. In a `do while`, the boolean check
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is not done until after the execution of an iteration.
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```php
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$num = 0;
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do {
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echo "Do while $num\n";
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++$num;
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} while ($num < 5);
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```
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`for` loops allow you to create a more concise while loop.
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Inside the parentheses, the left section creates a variable before the loop
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starts, the middle section is the check that is done at the beginning of each loop
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and the third section is executed after each loop.
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```php
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for ($i = 0; $i < 10; $i++) {
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echo "For loop $i\n";
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}
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```
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A `foreach` loop allows you to easily loop over an array.
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An array is a list of data stored together.
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The `as` keyword lets you assign a variable to the value
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in the array for the current iteration of the loop.
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```php
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$set = [1, 2, 3, 4, 5];
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foreach ($set as $num) {
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echo "Array value $num\n";
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}
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```
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In loops, you can use the keyword `break` to stop the loop execution
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no matter how many more iterations should run.
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```php
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$values = ['one', 'two', 'three'];
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foreach ($values as $value) {
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if ($value === 'two') {
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break;
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}
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echo "Break $value\n";
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}
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```
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The `continue` keyword stops executing the current loop iteration,
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but then allows the loop to continue with other iterations.
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```php
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$values = ['one', 'skip', 'three'];
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foreach ($values as $value) {
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if ($value === 'skip') {
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continue;
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}
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echo "Continue $value\n";
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}
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```
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