Checking the type of a string in PHP
If you’re working with PHP, you might have come across a situation where you need to check the type of the string. For instance, you might want to check if the string is a number, alphabetic, alphanumeric, or a binary string.
PHP has this set of functions prefixed with ctype_ which can effortlessly check the type of a string. Let’s take a look at them one by one. By the way, these functions have been available since PHP 4.0.4.
- Checking if the string is alphabetic
- Checking if the string is numeric
- Checking if the string is alphanumeric
- Checking if the string is binary
- Checking if the string is whitespace
- Checking if the string is printable
- Checking if the string is a control character
- Checking if the string is a graph character
- Checking if the string is a lowercase
- Checking if the string is an upper case
- Checking if the string is a punctuation
Checking if the string is alphabetic
To check if the string contains only alphabetic characters, you can use the ctype_alpha function like so.
ctype_alpha('Hello World'); // true
ctype_alpha('Hello World 123'); // false
Checking if the string is numeric
To check if the string contains only numeric characters, you can use the ctype_digit function like so.
ctype_digit('123'); // true
ctype_digit('Hello World'); // false
Checking if the string is alphanumeric
To check if the string contains only alphanumeric characters, you can use the ctype_alnum function like so.
ctype_alnum('Hello World 123'); // true
ctype_alnum('Hello World 123!'); // false
Checking if the string is binary
To check if the string contains only binary characters, you can use the ctype_xdigit function like so.
ctype_xdigit('0F'); // true
ctype_xdigit('0FZ'); // false
Checking if the string is whitespace
To check if the string contains only whitespace characters, you can use the ctype_space function like so.
ctype_space("\n\r\t"); // true
ctype_space("Hello World"); // false
Checking if the string is printable
To check if the string contains only printable characters, you can use the ctype_print function like so.
Here, a string is not printable if it contains any control characters like \n, \r, \t, etc.
ctype_print("Hello World"); // true
ctype_print("Hello World\n"); // false
Checking if the string is a control character
To check if the string contains only control characters, you can use the ctype_cntrl function like so.
ctype_cntrl("\n\r\t"); // true
ctype_cntrl("Hello World"); // false
Checking if the string is a graph character
To check if the string contains only graph characters, you can use the ctype_graph function like so.
This means any printable character(s) except space.
ctype_graph("Hello World"); // true
ctype_graph("Hello World\n"); // false
Checking if the string is a lowercase
To check if the string contains only lowercase characters, you can use the ctype_lower function like so.
ctype_lower("hello world"); // true
ctype_lower("Hello World"); // false
Checking if the string is an upper case
To check if the string contains only upper case characters, you can use the ctype_upper function like so.
ctype_upper("HELLO WORLD"); // true
ctype_upper("Hello World"); // false
Checking if the string is a punctuation
To check if the string contains only punctuation characters, you can use the ctype_punct function like so.
ctype_punct("*&$()!"); // true
ctype_punct("Hello World!"); // false
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