What are the common functions in PHP programming?

PHP is a programming language commonly used for web development. It has a rich function library to support various operations and functions. In this article, we will introduce common functions in PHP programming.

1. String functions

In PHP programming, string functions are used to process strings. Common string functions include:

• strlen() function: used to get the length of a string.
• substr() function: used to obtain a substring.
• strtoupper() function: used to convert strings to uppercase.
• strtolower() function: used to convert strings to lowercase.
• str_replace() function: used to replace a certain character in a string.
• strpos() function: used to find specified characters or substrings in a string.

2. Array function

In PHP programming, array functions are used to process arrays. Common array functions include:

• count() function: used to get the number of elements in an array.
• array_push() function: used to add elements to the end of the array.
• array_pop() function: used to remove elements from the end of the array.
• array_shift() function: used to delete elements from the beginning of the array.
• array_unshift() function: used to add elements at the beginning of the array.
• array_slice() function: used to obtain a subset of the array.

3. File function

In PHP programming, the file function is used to process files. Common file functions include:

• fopen() function: used to open files.
• fread() function: used to read data from files.
• fwrite() function: used to write data to a file.
• fclose() function: used to close the file.

4. Database functions

In PHP programming, database functions are used to process the database. Common database functions include:

• mysql_connect() function: used to connect to the database.
• mysql_query() function: used to send queries to the database.
• mysql_fetch_array() function: used to get rows from query results.
• mysql_num_rows() function: used to obtain the number of rows in query results.
• mysql_close() function: used to close the database connection.

5. Time and date functions

In PHP programming, time and date functions are used to process time and date. Common time and date functions include:

• date() function: used to obtain the current time and date.
• time() function: used to obtain the timestamp of the current time.
• strtotime() function: used to convert a string into a timestamp.
• mktime() function: used to obtain the timestamp of a specified date.
• date_diff() function: used to calculate the difference between two dates.

Summary

The above are the common function classifications and commonly used functions in PHP programming. They are the basic knowledge that must be mastered in PHP development. We can call these functions as needed to implement various operations and functions. Proficiency in these functions will help us write PHP programs better.

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