As mentioned above, only ASCII characters from 32 to 126 are considered printable, all others, including UTF-8 encoded characters are always considered unprintable, no matter what your locale settings are. Therefore, e.g. German "ä", the Euro sign "€" or the British pound symbol "£" will never be printable. If you need to check any characters for "printability" beyond the standard ASCII range, use a regular expression or write a specific function yourself.
See also this discussion: https://grokbase.com/t/php/php-i18n/102tkqe6rk/ctype-print-returns-false-for-british-pound-symbol-and-non-ascii-symbols
ctype_print
(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
ctype_print — 检测可打印字符
参数
返回值
如果在当前的语言环境下 text 里面的每个字符都能被实际输出（包括空白），那么就返回
true；如果 text 包含控制字符或者没有任何输出的字符，那么就返回
false。当使用空字符串调用时，结果始终为 false。
示例
示例 #1 ctype_print() 示例
<?php
$strings = array('string1' => "asdf\n\r\t", 'string2' => 'arf12', 'string3' => 'LKA#@%.54');
foreach ($strings as $name => $testcase) {
if (ctype_print($testcase)) {
echo "The string '$name' consists of all printable characters.\n";
} else {
echo "The string '$name' does not consist of all printable characters.\n";
}
}
?>以上示例会输出：
The string 'string1' does not consist of all printable characters. The string 'string2' consists of all printable characters. The string 'string3' consists of all printable characters.
参见
- ctype_cntrl() - 检测控制字符
- ctype_graph() - 检测除空格外的任何打印字符
- ctype_punct() - 检测可打印的字符是不是不包含空白、数字和字母
- IntlChar::isprint() - Check if code point is a printable character
add a note
User Contributed Notes 4 notes
ClayDragon ¶
6 years ago
Anonymous ¶
12 years ago
Only ascii 32 thru 126 (inclusive) are considered printable. Tab (ascii 7), carriage return (ascii 13), linefeed (ascii 10) etc may produce output but are not considered printable.
harry at upmind dot com ¶
3 years ago
You can use this function to detect if a string is "binary".
<?php
/**
* Determine whether the given value is a binary string by checking to see if it contains only printable characters.
*
* @param string $value
*
* @return bool
*/
function isBinary($value): bool
{
// remove "unprintable" whitespace characters (tabs, newlines etc)
$string = preg_replace('/\s/', '', (string)$value);
return !empty($string) && !ctype_print($string);
}
?>
