The PHP Ctype extension is an extension built into PHP4.2 since PHP4.2. Note that the Ctype series functions only have one string type parameter, and they return a Boolean value.
$str = "0.1123";
//Check whether all characters in the string are numeric
echo "ctype_digit:" . ctype_digit($str); //Empty
//Detect whether it is a numeric string, which can be negative and decimal
echo "is_numberic:" . is_numeric($str); //1
From the above, we can see the difference between ctype_digit() and is_numberic().
Chinese translation
The Ctype function is a built-in string measurement function in PHP. There are mainly the following types
ctype_alnum -- Check for alphanumeric character(s)
Detection whether it contains only [A-Za-z0-9]
ctype_alpha -- Check for alphabetic character(s)
Detection whether it contains only [A-Za-z]
ctype_cntrl -- Check for control character(s)
Check whether it only contains characters such as "\n\r\t" and control characters
ctype_digit -- Check for numeric character(s)
When checking, it is a string containing only numeric characters (0-9)
ctype_graph -- Check for any printable character(s) except space
Check whether it is a string containing only characters (except spaces) that can be printed out
ctype_lower -- Check for lowercase character(s)
Check whether all characters are English letters and are in lowercase
ctype_print -- Check for printable character(s)
Check whether it is a string containing only characters that can be printed out
ctype_punct -- Check for any printable character which is not whitespace or an alphanumeric character
Check whether it is a printable character that contains only non-number/character/space
ctype_space -- Check for whitespace character(s)
Check whether it contains only characters and spaces such as " ".
ctype_upper -- Check for uppercase character(s)
Check whether all characters are in English and are capitalized
ctype_xdigit -- Check for character(s) representing a hexadecimal digit
Check whether it is a hexadecimal string, only include "0123456789abcdef"
There are examples
When we usually encounter simple filtering of some forms, we are often reluctant to write regulars. In terms of efficiency, regulars are also one of the reasons that affect PHP's running speed, so try not to try regulars when we can not try regulars. Fortunately PHP has taken this into consideration for us and provides me with the Ctype function. Here are some brief introductions to some Ctype functions to be used as a backup:
1. ctype_alnum — Check for alphanumeric character(s) Check that the string contains only numbers or letters, which is equivalent to regular [A-Za-z0-9]. There is a return value. Returns TRUE when successful, and FALSE if failed;
[
<?php
$strings = array('AbCd1zyZ9', 'foo!#$bar');
foreach ($strings as $testcase) {
if (ctype_alnum($testcase)) {
echo "The string $testcase consists of all letters or digits.\n"; \\ Output The string AbCd1zyZ9 consists of all letters or digits.
} else {
echo "The string $testcase does not consist of all letters or digits.\n"; \\ Output The string foo!#$bar does not consist of all letters or digits.
}
}
?>
2. ctype_alpha — Check for alphabetic character(s) Check that only letters are included in the string. Return TRUE when successful, and FALSE if failed;
<?php
$strings = array('KjgWZC', 'arf12');
foreach ($strings as $testcase) {
if (ctype_alpha($testcase)) {
echo "The string $testcase consists of all letters.\n"; \\ Output The string KjgWZC consists of all letters.
} else {
echo "The string $testcase does not consist of all letters.\n";<span style="white-space:pre"> </span>\\ Output The string arf12 does not consist of all letters.
}
}
?>
3. ctype_cntrl — Check for control character(s) Check whether the string contains only control characters such as " '\n' '\r' '\t' ".
<?php
$strings = array('string1' => "\n\r\t", 'string2' => 'arf12');
foreach ($strings as $name => $testcase) {
if (ctype_cntrl($testcase)) {
echo "The string '$name' consists of all control characters.\n"; \\ Output The string 'string1' consists of all control characters.
} else {
echo "The string '$name' does not consist of all control characters.\n"; \\ The string 'string2' does not consist of all control characters.
}
}
?>
4. ctype_digit — Check for numeric character(s) Check whether only numbers are included in the string
<?php
$strings = array('1820.20', '10002', 'wsl!12');
foreach ($strings as $testcase) {
if (ctype_digit($testcase)) {
echo "The string $testcase consists of all digits.\n";
} else {
echo "The string $testcase does not consist of all digits.\n";
}
}
?>