Javascript regexp 检查输入是否只是整数 (int) ，并检查另一个是否只有 2 个小数位的数字
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regexp to check if input is only whole numbers (int) , and to check if another is only numbers with 2 decimal places
提问by re1man
I want to know what a regex would look like for:
我想知道正则表达式的样子：
- only whole numbers
- only numbers with less than or equal to two decimal places (23, 23.3, 23.43)
- 只有整数
- 只有小于或等于两位小数的数字 (23, 23.3, 23.43)
回答by NullUserException
Only whole numbers:
只有整数：
/^\d+$/
# explanation
\d match a digit
+ one or more times
Numbers with at most 2 decimal places:
最多保留 2 位小数的数字：
/^\d+(?:\.\d{1,2})?$/
# explanation
\d match a digit...
+ one or more times
( begin group...
?: but do not capture anything
\. match literal dot
\d match a digit...
{1,2} one or two times
) end group
? make the entire group optional
Notes:
笔记：
- The slashes denote start and end of pattern
^and$are start and end of string anchors. Without these, it will look for matches anywhere in the string. So/\d+/matches'398501', but it also matches'abc123'. The anchors ensures the entirestring matches the given pattern.- If you want to allow negative numbers, add a
-?before the first\d. Again,?denotes "zero or one time."
- 斜线表示模式的开始和结束
^和$是字符串锚点的开始和结束。如果没有这些，它将在字符串中的任何位置查找匹配项。所以/\d+/匹配'398501'，但它也匹配'abc123'。锚点确保整个字符串匹配给定的模式。- 如果要允许负数，请
-?在第一个\d. 再次?表示“零次或一次”。
Usage example:
用法示例：
var rx = new RegExp(/^\d+(?:\.\d{1,2})?$/);
console.log(rx.test('abc')); // false
console.log(rx.test('309')); // true
console.log(rx.test('30.9')); // true
console.log(rx.test('30.85')); // true
console.log(rx.test('30.8573')); // false
回答by toon81
I. [1-9][0-9]*if the number should be greater than zero (any series of digits starting with a nonzero digit). if it should be zero or more: (0|[1-9][0-9]*)(zero or a nonzero number). If it can be negative: (0|-?[1-9][0-9]*)(zero or a nonzero number that can have a minus before it.)
I.[1-9][0-9]*如果数字应该大于零（任何以非零数字开头的数字系列）。如果它应该是零或更多：（(0|[1-9][0-9]*)零或非零数字）。如果它可以是负数：（(0|-?[1-9][0-9]*)零或一个非零数字，前面可以有一个减号。）
II. a regex like I. followed by: (\.[0-9]{1,2})?that means, optionally a dot followed by one or two digits.
二、像 I. 一样的正则表达式。后跟：(\.[0-9]{1,2})?这意味着，可以选择一个点后跟一位或两位数字。
回答by Alex Peattie
Whole numbers only
仅限整数
/\d+/
One or two decimal places:
一位或两位小数：
/\d(\.\d{1,2})?/
