正则表达式 - C# 中的 2 个字母和 2 个数字
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Regular Expression - 2 letters and 2 numbers in C#
提问by Dan-SP
I am trying to develop a regular expression to validate a string that comes to me like: "TE33" or "FR56" or any sequence respecting 2 letters and 2 numbers.
我正在尝试开发一个正则表达式来验证出现在我面前的字符串，例如：“TE33”或“FR56”或任何关于 2 个字母和 2 个数字的序列。
The first 2 characters must be alphabetic and 2 last caracters must be numbers.
前 2 个字符必须是字母，最后 2 个字符必须是数字。
I tried many combinations and I didn't have success. Last one I tried:
我尝试了很多组合，但都没有成功。我试过的最后一个：
if(Regex.IsMatch(myString, "^[A-Za-z]{2}[0-9]{2}")){
}
采纳答案by Ry-
You're missing an ending anchor.
你缺少一个结束锚点。
if(Regex.IsMatch(myString, "^[A-Za-z]{2}[0-9]{2}\z")) {
// ...
}EDIT: If you can have anything between an initial 2 letters and a final 2 numbers:
编辑：如果您可以在开头的 2 个字母和最后的 2 个数字之间有任何内容：
if(Regex.IsMatch(myString, @"^[A-Za-z]{2}.*\d{2}\z")) {
// ...
}回答by Jason Carter
This should get you for starting with two letters and ending with two numbers.
这应该让您以两个字母开头并以两个数字结尾。
[A-Za-z]{2}(.*)[0-9]{2}
If you know it will always be just two and two you can
如果你知道它总是只有两个和两个，你可以
[A-Za-z]{2}[0-9]{2}
回答by James Hill
Just for fun, here's a non-regex (more readable/maintainable for simpletons like me) solution:
只是为了好玩，这是一个非正则表达式（对于像我这样的简单者来说更具可读性/可维护性）解决方案：
string myString = "AB12";
if( Char.IsLetter(myString, 0) &&
Char.IsLetter(myString, 1) &&
Char.IsNumber(myString, 2) &&
Char.IsNumber(myString, 3)) {
// First two are letters, second two are numbers
}
else {
// Validation failed
}
EDIT
编辑
It seems that I've misunderstood the requirements. The code below will ensure that the first two characters and last two characters of a string validate (so long as the length of the string is > 3)
看来我误解了要求。下面的代码将确保字符串的前两个字符和后两个字符有效（只要字符串的长度 > 3）
string myString = "AB12";
if(myString.Length > 3) {
if( Char.IsLetter(myString, 0) &&
Char.IsLetter(myString, 1) &&
Char.IsNumber(myString, (myString.Length - 2)) &&
Char.IsNumber(myString, (myString.Length - 1))) {
// First two are letters, second two are numbers
}
else {
// Validation failed
}
}
else {
// Validation failed
}
