Detailed explanation of PHP built-in function library

PHP built-in function library contains various functions to simplify code and improve development efficiency, including: Type conversion function: Convert data type from one to another. String operation functions: used to process strings, such as searching, extracting and calculating length. Math functions: Perform common mathematical operations such as calculating absolute values, square roots, and rounding. Array functions: used to manipulate arrays, such as counting the number of elements, merging, and checking whether an element exists.

Detailed explanation and practical cases of PHP built-in function library

PHP built-in function library is a huge collection, including Functions that perform various common tasks. These functions can simplify your code and improve your development efficiency.

Type conversion function

Type conversion function is used to convert one data type to another data type. Some common type conversion functions include:

• intval(): Convert a string to an integer
• floatval(): Convert a string to an integer Convert string to floating point number
• strval(): Convert integer or floating point number to string

String operation function

String operation functions are used to process strings. Some common string manipulation functions include:

• strlen(): Returns the length of the string
• strpos(): Search The first occurrence of a substring in a string
• substr(): Extract a substring from a string

Mathematical function

Math functions are used to perform common mathematical operations. Some common math functions include:

• abs(): Returns the absolute value
• sqrt(): Calculates the square root
• round(): Round numbers

Array function

Array function is used to operate arrays. Some common array functions include:

• count(): Returns the number of array elements
• array_merge(): Merges two Array
• in_array(): Check whether an element exists in the array

Practical case: Use PHP built-in functions to read and parse CSV files

The following code shows a practical example of how to use PHP built-in functions to read and parse CSV files:

<?php
// 打开 CSV 文件
$file = fopen('data.csv', 'r');

// 逐行读取 CSV 文件
while (($row = fgetcsv($file)) !== FALSE) {
    // 遍历每行数据并打印出来
    foreach ($row as $value) {
        echo $value . ',';
    }
    echo "\n";
}

// 关闭 CSV 文件
fclose($file);
?>

This code snippet will read the CSV file line by line and use fgetcsv() The function parses each row of data into an array. Then, it iterates through each element in the array and prints them.

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