正则表达式:小写、点、零空格 [英] Regular Expressions: low-caps, dots, zero spaces

问题描述

如何编写一个表达式来检查字符串中是否存在低大写字母、点和空格?

how do I write an expression which checks for lowcaps, dots, and without any white space in the string?

到目前为止，下面的代码试图检查低大写字母和点(无论如何它都不起作用！)但我不知道如何添加空格的表达式.

the code below so far was trying to check for lowcaps and dots (it does not work anyway!) but I don't know how to add in the expression for white spaces.

# check for matches of lowcaps or lowcaps with a dot
if (!preg_match('/([a-z0-9]|[a-z0-9\.])/', $cst_value))
{
  $error = true;
  echo ' please use lowcaps only with dot(s) and without any spacing.';
}

推荐答案

[a-z0-9.] 匹配小写字母、数字或点.
[^a-z0-9.] 匹配所有不是小写字母、数字或点的字符.
因此，如果 /[^a-z0-9.]/ 匹配字符串包含除 lc-letter、digit 或 dot 以外的任何内容的任何位置.如果不匹配，则满足您的条件.

[a-z0-9.] matches a lower-case letter or a digit or a dot.
[^a-z0-9.] matches all characters that are not a lower-case letter or a digit or a dot.
So if /[^a-z0-9.]/ matches anywhere the string contains something other than lc-letter,digit or dot. If it does not match your condition is fulfilled.

if ( !preg_match('/[^a-z0-9.]/', $cst_value) ) {
  // only lower-case letters, digits or dots
}

或不带数字

if ( !preg_match('/[^a-z.]/', $cst_value) ) {
  // only lower-case letters or dots
}

<小时>

更新:示例:

---

update: example:

foreach( array('abcdef', 'abc de', 'abc.de', 'aBcde') as $cst_value) {
  echo $cst_value, ': ';
  if ( !preg_match('/[^a-z.]/', $cst_value) ) {
    echo " ok.\n";
  }
  else {
    echo "failure\n";
  }
}

印刷品

abcdef:  ok.
abc de: failure
abc.de:  ok.
aBcde: failure

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