PHP function encyclopedia: learn to use various functions to achieve functions

PHP is a commonly used dynamic scripting language that is widely used in web development. As a PHP developer, mastering the use of various functions is crucial for rapid development and improved efficiency. This article will introduce some commonly used PHP functions to help readers learn to use various functions to achieve functions.

1. String processing function

1. strlen(): Get the length of the string.
2. strtolower(): Convert the string to lowercase.
3. strtoupper(): Convert the string to uppercase.
4. strpos(): Find the position of a substring in a string.
5. explode(): Split the string into an array according to the specified delimiter.

2. Array processing function

1. count(): Count the number of elements in the array.
2. array_keys(): Get all keys of the array.
3. array_values(): Get all the values ​​of the array.
4. array_push(): Add one or more elements to the end of the array.
5. array_pop(): Delete the element at the end of the array.

3. File processing function

1. file_exists(): Determine whether the file exists.
2. fopen(): Open a file.
3. fread(): Read the specified length of content from the file.
4. fwrite(): Write content to the file.
5. fclose(): Close an open file.

4. Date and time functions

1. date(): Get the current date and time.
2. strtotime(): Convert datetime string to timestamp.
3. time(): Get the timestamp of the current time.
4. mktime(): Creates a timestamp based on the specified date and time.
5. strftime(): Format the timestamp into the specified date and time string.

5. Database function

1. mysqli_connect(): Connect to the MySQL database.
2. mysqli_query(): Execute SQL query.
3. mysqli_fetch_array(): Get a row of data from the query results.
4. mysqli_num_rows(): Counts the number of rows in query results.
5. mysqli_close(): Close the connection to the database.

6. Encryption and decryption functions

1. md5(): MD5 encryption of strings.
2. sha1(): SHA1 encrypts the string.
3. base64_encode(): Base64 encode the string.
4. base64_decode(): Decode the Base64 encoded string.
5. password_hash(): Use password hashing algorithm to encrypt the password.

7. Other commonly used functions

1. include(): Introduce a file.
2. is_numeric(): Determine whether a variable is a number.
3. rand(): Generate a random number within the specified range.
4. htmlspecialchars(): Convert special characters to HTML entities.
5. preg_match(): Use regular expressions for matching.

The above are only some commonly used PHP functions. The powerful and rich function library of PHP language can meet various development needs. Proficient in using these functions will greatly improve development efficiency. Of course, there are many other useful functions waiting to be explored and learned. I hope this article can help readers and let them better use PHP functions to realize their own functions.

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