How to convert PHP letters to uppercase and lowercase

1. Converting a string to lowercase

Strtolower (): This function converts all characters of the passed-in string argument to lowercase and puts the string back in a small form

　　2. Turn the characters into uppercase

Strtoupper (): The function, in contrast to the Strtolower function, converts the characters of the passed-in character argument to uppercase and returns the string in uppercase. The usage is the same as the Strtolowe ().

　3. Converts the first character of a string to uppercase

Ucfirst (): The function is to change the first character of the string to uppercase, which returns a string with the first character capitalized. Use the same as Strtolowe ().

　　4. Converts the first character of each word in a string to uppercase

Ucwords (): This function capitalizes the first character of each word in the passed-in string. such as "Hello World", after the function is processed, will return "Hello Word". The usage is the same as Strtolowe ().