How to get the first number of array in php-PHP Problem-php.cn

How to get the first number of array in php

青灯夜游

Release： 2023-03-17 17:28:02

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Interception method: 1. Use array_slice() to intercept the first N elements of the array. Just set the second parameter to 0 and the third parameter to N. The syntax is "array_slice($arr, 0,N)"; use the array_splice() function to intercept the first N elements of the array. Just set the second parameter to 0 and the third parameter to N. The syntax is "array_splice($arr,0,N) ".

How to get the first number of array in php

The operating environment of this tutorial: windows7 system, PHP8 version, DELL G3 computer

In php, you can use array_slice() function or array_splice() function to intercept the first N elements of the array.

Method 1. Use array_slice() function to intercept the first N elements of the array

array_slice() function is provided by PHP to intercept arrays A function that extracts a fragment from an array. The syntax is as follows:

array_slice(array,start,length,preserve)

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Parameter description:

Parameter	Description
array	Required. Specifies an array.
start	Required. numerical value. Specifies the starting position of the element to be retrieved. 0 = first element. If the value is set to a positive number, it will be taken from front to back. If the value is set to a negative number, the absolute value of start is taken from back to front. -2 means start from the second to last element of the array.
length	Optional. numerical value. Specifies the length of the returned array. If the value is set to an integer, this number of elements is returned. If this value is set to a negative number, the function will terminate fetching this far from the end of the example array. If this value is not set, all elements starting from the position set by the start parameter to the end of the array are returned.
preserve	Optional. Specifies whether the function retains key names or resets key names. Possible values: true - Reserve key name false - default. Reset key name

Example: intercept the first N elements of the array

Want To intercept the first N elements of the array, just set the second parameter start to 0 and the third parameter length to N.

<?php
header("Content-type:text/html;charset=utf-8");
$arr = array(10,12,20,25,24);
echo "原数组：";
var_dump($arr); 

echo "截取数组前2位的元素片段：";
$result = array_slice($arr,0,2); //截取数组前2位的元素
var_dump($result);

echo "截取数组前3位的元素片段：";
$result = array_slice($arr,0,3); //截取数组前3位的元素
var_dump($result);
?>

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Output result

How to get the first number of array in php

##Method 2. Use array_splice() function to intercept the first N elements of the array

When the array_splice() function deletes some elements of the array, it will form these deleted elements into a new array and then return the new array; therefore, the array_splice() function can be used to intercept the array fragment.

array_splice(array1,start,length,array2)

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Parameter description:

ParameterDescriptionRequired. Specifies an array. Required. numerical value. Specifies the starting position of deleted elements. 0 = first element. If the value is set to a positive number, removal begins at the offset specified by the value in the array. If the value is set to a negative number, removal begins at the offset specified by the value from the end of the array. -2 means start from the second to last element of the array. Optional. numerical value. Specifies the number of elements to be removed, which is also the length of the returned array. If this value is set to a positive number, remove this number of elements. If this value is set to a negative number, all elements from start to length inverse of the end of the array are removed. If this value is not set, all elements from the position set by the start parameter to the end of the array are removed. Optional. Specifies the array with the elements to be inserted into the original array. If there is only one element, it can be set to a string and does not need to be set to an array.


array1
start
length
array2

Same as the array_slice() function, just set the second parameter start of the function to 0 and the third parameter length to N.

<?php
header("Content-type:text/html;charset=utf-8");
$arr = array(10,12,20,25,24);
echo "原数组：";
var_dump($arr); 

echo "截取数组前1位的元素片段：";
$result = array_splice($arr,0,1); //截取数组前1位的元素
var_dump($result);

echo "截取数组前2位的元素片段：";
$result = array_splice($arr,0,2); //截取数组前2位的元素
var_dump($result);

echo "截取数组前3位的元素片段：";
$result = array_splice($arr,0,3); //截取数组前3位的元素
var_dump($result);
?>

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Output results

How to get the first number of array in php

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