PHP - preg_match - 如何匹配以零开头的数字
I am trying to use preg_match to match numbers that start with a zero to indicate an invalid input. Numbers such as 01, 0023, 00.4 are invalid; however numbers such as 0.12 are valid. The input would be a calculator entry, such as 09 * 108 + 0.19 + 4009. In this case, the expression would be invalid because of the 09.
So far my expression looks like: preg_match("/[^1-9]+0[0-9]+/", $subject)
What I tried to do was match when a zero precedes any string of digits, but is also not preceded by another string of digits. So 109 is valid, but 1+09 is invalid. However it isn't working for cases like 1 + 4009.
我正在尝试使用preg_match匹配以零开头的数字来表示无效输入。 到目前为止，我的表达式如下： 我尝试做的是匹配，当零在任何数字字符串之前，但也不在另一个数字字符串之前。 所以 01 code>， 0023 code>， 00.4 code>等数字无效; 但是 0.12 code>之类的数字是有效的。 输入将是计算器条目，例如 09 * 108 + 0.19 + 4009 code>。 在这种情况下，由于 09 code>，表达式将无效。 p>
preg_match（“/ [^ 1-9] +0 [0-9] + /”，$ subject） code>
109 code>有效，但1 + 09无效。 但是它不适用于 1 + 4009 code>等情况。 p>
div>
preg_match('/\b0[0-9]+(?:\.[0-9]+)?\b/', $subject)
\b for word boundary.