How to write a two-dimensional array to a file in php (a brief analysis of the method)

PHP is a very popular scripting language that is commonly used to develop web applications. In PHP, we often need to write data to files. For a two-dimensional array, such as a multi-dimensional associative array, how to write it to a file? In this article, we will learn how to write a 2D array to a file in PHP.

In PHP, we can use the file_put_contents() function to write strings to files. However, if we want to write a multidimensional associative array to a file, we need to convert it to JSON format before writing it to the file. JSON format is a lightweight data exchange format, which is very suitable for us to write data into files in the form of strings.

The following is a code example for writing a two-dimensional array to a file:

$data = array(
    array('name' => '张三', 'age' => 18),
    array('name' => '李四', 'age' => 20),
    array('name' => '王五', 'age' => 22)
);

$jsonData = json_encode($data, JSON_UNESCAPED_UNICODE);
file_put_contents('data.json', $jsonData);

In the above code, we first define a two-dimensional array $data, which contains three sizes is an associative array of 2, each associative array has two key-value pairs: name and age. We then use the json_encode() function to convert $data to a JSON formatted string. The second parameter is used to specify that Unicode characters are not to be escaped, which ensures that Chinese characters are displayed correctly.

Finally, we use the file_put_contents() function to write the JSON-formatted string into a file named data.json. The first parameter of the file_put_contents() function here is the file name, and the second parameter is the content to be written.

When we run this code, a file named data.json will be generated in the current directory, which contains all the data in the $data array.

In actual development, we may need to write data to other types of files, such as CSV format files. CSV (Comma Separated Values) is a common data format that uses commas as field separators and newlines as record separators. The following is a code example for writing a two-dimensional associative array to a CSV file:

$data = array(
    array('name' => '张三', 'age' => 18),
    array('name' => '李四', 'age' => 20),
    array('name' => '王五', 'age' => 22)
);

$fp = fopen('data.csv', 'w');
foreach ($data as $line) {
    fputcsv($fp, $line);
}
fclose($fp);

In the above code, we first define a two-dimensional associative array $data of size 3, which contains three Associative arrays, each associative array contains two key-value pairs named name and age. We then use the fopen() function to open the file named data.csv, set the file mode to write mode ("w"), and store the returned file pointer into the $fp variable.

Next, we use a foreach loop to loop through each associative array in the $data array and pass it as a parameter to the fputcsv() function. This function writes a line of comma-separated values ​​to a file. Finally, we close the file handle using the fclose() function.

When we run this code, a file named data.csv will be generated in the current directory, which contains all the data in the $data array. You can open this CSV file with Excel or other spreadsheet software, and you can see that the data inside has been arranged in comma-separated format.

Conclusion

Writing a two-dimensional array to a file in PHP is very simple. You just need to convert it to a suitable format and then use the corresponding function to write it to the file. In addition to JSON and CSV formats, there are many other data formats to choose from, and developers can choose according to their specific needs.

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