Application skills of PHP common function libraries

PHP is a powerful programming language that is often used for the development of web applications. In PHP, there are many commonly used function libraries that can help developers easily complete various operations. This article will introduce several commonly used function libraries and their application techniques.

1. String function library

The string function library is generally used for string operations, including string length, string concatenation, string interception, etc. The following are several commonly used string functions:

strlen() function is used to obtain the length of a string, for example:

$str = "Hello World!";
echo strlen($str); //输出13

str_replace() function is used to replace characters in a string, for example :

$str = "Hello World!";
echo str_replace('World', 'PHP', $str); //输出Hello PHP!

substr() function is used to intercept strings, for example:

$str = "Hello World!";
echo substr($str, 0, 5); //输出Hello

2. Array function library

The array function library is generally used for array operations, including array operations Length, array sorting, array merging, etc. The following are several commonly used array functions:

count() function is used to obtain the length of the array, for example:

$arr = array(1,2,3,4,5);
echo count($arr); //输出5

sort() function is used to sort the array in ascending order, for example:

$arr = array(3,2,1,5,4);
sort($arr);
print_r($arr); //输出Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 )

array_merge() function is used to merge multiple arrays, for example:

$arr1 = array(1,2);
$arr2 = array(3,4);
$arr3 = array(5,6);
print_r(array_merge($arr1,$arr2,$arr3)); //输出Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 )

3. Date function library

The date function library is generally used for date operations, including obtaining the current time. , format date, etc. The following are several commonly used date functions:

time() function is used to obtain the timestamp of the current time, for example:

echo time(); //输出1606211876

date() function is used to format dates, for example:

echo date('Y-m-d H:i:s'); //输出2020-11-24 17:38:46

strtotime() function is used to convert a string into a timestamp, for example:

echo strtotime('2020-11-24 17:38:46'); //输出1606211926

4. File function library

The file function library is generally used for file operations. Including creating files, reading files, deleting files, etc. The following are several commonly used file functions:

fopen() function is used to open a file, for example:

$file = fopen("test.txt", "w");
fwrite($file, "Hello World. Testing!");
fclose($file);

file_get_contents() function is used to read file contents, for example:

echo file_get_contents("test.txt"); //输出Hello World. Testing!

unlink() function is used to delete files, for example:

unlink("test.txt");

Conclusion

Through the introduction of the above function libraries and functions, I believe everyone has a deeper understanding of PHP's processing logic. understanding. In actual PHP development, we can choose different function libraries or functions as needed to complete programming tasks more efficiently.

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