Share a summary of several character functions in PHP_PHP Tutorial

Below is a summary of several character functions in PHP. To summarize:

1)ucfirst
Change the first letter to uppercase, such as
$string = "this is my web development blog";

echo ucfirst($string);

// Output: This is my web development blog

2) lcfirst, change the first letter to lowercase
$string = "This is my Web Development Blog";

echo lcfirst($string);

// Output: this is my Web Development Blog

3) strtoupper, capitalize the entire string
$string = "this is my web development blog";

echo strtoupper($string);

// Output: THIS IS MY WEB DEVELOPMENT BLOG

4) strtolower, change the entire string to lowercase
$string = "tHiS is mY WeB DevElOpMenT bLoG";

echo strtolower($string);

// Output: this is my web development blog

5) ucwords(), you can capitalize the first letter of each word in the sentence, such as
$string = "this is my web development blog";

echo ucwords($string);

// Output: This Is My Web Development Blog