How to use PHP's string functions?

How to use string functions in PHP?

PHP provides a series of built-in string functions that can be used to manipulate and process text data. These function operations include text formatting, search and replacement, comparison and validation, etc.

Basic string operations

Convert the string to lowercase Extract a substring from a string Search and replace specific substrings in a string

Function	Description
strlen()	Returns the length of the string
strtoupper()	Convert the string to uppercase
##strtolower()
substr()
str_replace()

Text formatting

Function Description ##trim() ltrim() rtrim() wordwrap() ##nl2br() Search and Replace

From string Delete leading and trailing blank characters
Remove the left blank characters from the string
Remove the right whitespace characters from the string
Wrap the string to the specified width
Convert the newline character to HTML ;< td> Tag >

Function Description strpos() strrpos() preg_match( ) preg_replace() String comparison

Find the position of the substring in the string
Find the position of the substring starting from the end of the string
Search strings using regular expressions
Replace characters using regular expressions Substring in string

Function Description ##strcmp() strcasecmp() strstr() str_starts_with() str_ends_with() String validation

Compare two strings
Compares two strings case-insensitively
Check whether a string contains another string
Check whether a string begins with another string A string starts with
Check if a string ends with another string

Function Description filter_var() is_string() is_numeric() ctype_alpha() ctype_digit() Practical case

Validate the string using predefined validation rules
Check if the variable is a string
Check if the variable is a number
Check if the string contains only letters
Check whether the string only contains numbers

Use the string introduced above function, we can take the following text as an example to process:

We can use the

trim()

function to delete the leading and trailing blank characters:

and then usestrtoupper ()function converts text to uppercase:

Finally, use thepreg_replace()function to replace periods with colons:

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