php 如何检测字符串中是否有换行符？
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How to detect if a string has a new line break in it?
提问by TK123
This doesn't work:
这不起作用：
$string = 'Hello
world';
if(strpos($string, '\n')) {
echo 'New line break found';
}
else {
echo 'not found';
}
Obviously because the string doesn't have the "\n" character in it. But how else can I check to see if there is a line break that is the result of the user pressing enter in a form field?
显然是因为字符串中没有“\n”字符。但是我还能如何检查是否有换行符是用户在表单字段中按下 Enter 的结果？
回答by rdlowrey
Your existing test doesn't work because you don't use double-quotes around your line break character ('\n'). Change it to:
您现有的测试不起作用，因为您没有在换行符 ( '\n')周围使用双引号。将其更改为：
if(strstr($string, "\n")) {
if(strstr($string, "\n")) {
Or, if you want cross-operating system compatibility:
或者，如果您想要跨操作系统兼容性：
if(strstr($string, PHP_EOL)) {
if(strstr($string, PHP_EOL)) {
Also note that strposwill return 0 and your statement will evaluate to FALSE if the first character is \n, so strstris a better choice. Alternatively you could change the strposusage to:
另请注意，strpos如果第一个字符是\n，则将返回 0 并且您的语句将评估为 FALSE ，因此strstr是更好的选择。或者，您可以将strpos用法更改为：
if(strpos($string, "\n") !== FALSE) {
echo 'New line break found';
}
else {
echo 'not found';
}
回答by Mouna Cheikhna
line break is \r\non windows and on UNIX machines it is \n.
so its search for PHP_EOLinstead of "\n" for cross-OS compatibility, or search for both "\r\n" and "\n".
换行符\r\n在 Windows 和 UNIX 机器上是\n。所以它搜索PHP_EOL而不是“\n”以获得跨操作系统兼容性，或者搜索“\r\n”和“\n”。
