rashmi agar
12 posts
Mar 07, 2025
9:58 PM
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When working with array.fill , there are times when you need to initialize an array with predefined values. Instead of using loops, PHP provides a built-in function called array_fill(), which simplifies this process. In this post, we'll dive into how array_fill() works, its syntax, use cases, and potential pitfalls.
What is array_fill()?
The array_fill() function is used to fill an array with a specific value starting from a given index. This is particularly useful when you need an array of default values or placeholders.
Syntax:
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array_fill(start_index, num_elements, value);
start_index – The index from which filling should begin.
num_elements – The number of elements to create.
value – The value to assign to each element.
Example Usage:
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$filledArray = array_fill(0, 5, "Hello");
print_r($filledArray);
Output:
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Array
(
[0] => Hello
[1] => Hello
[2] => Hello
[3] => Hello
[4] => Hello
)
In this example, an array with five elements is created, each initialized with "Hello" starting from index 0.
Using array_fill() with Non-Zero Indexes
You can start filling from any index, even negative ones:
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$filledArray = array_fill(-2, 3, "PHP");
print_r($filledArray);
Output:
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Array
(
[-2] => PHP
[-1] => PHP
[0] => PHP
)
Common Use Cases
Initializing arrays with default values.
Pre-allocating memory for arrays in large data operations.
Creating placeholder values for forms or configurations.
Limitations & Warnings
The num_elements parameter must be greater than 0, or it will throw a warning.
If using large numbers, memory consumption should be considered.
Alternative: array_fill_keys()
If you need to set values for specific keys instead of a sequential range, consider using array_fill_keys():
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$keys = ["one", "two", "three"];
$filledKeys = array_fill_keys($keys, "default");
print_r($filledKeys);
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