搜索2个特定字母，后跟4个数字正则表达式

Question

I need to check if a string begins with 2 specific letters and then is followed by any 4 numbers.

the 2 letters are "BR" so BR1234 would be valid so would BR7412 for example.

what bit of code do I need to check that the string is a match with the Regex in C#?

the regex I have written is below, there is probably a more efficient way of writing this (I'm new to RegEx)

[B][R][0-9][0-9][0-9][0-9]

Answer 1

You can use this:

Regex regex = new Regex(@"^BR\d{4}");

• ^ defines the start of the string (so there should be no other characters before BR)
• BR matches - well - BR
• \\d is a digit (0-9)
• {4} says there must be exactly 4 of the previously mentioned group ( \\d )

You did not specify what is allowed to follow the four digits. If this should be the end of the string, add a $ .

Usage in C#:

string matching = "BR1234";
string notMatching = "someOther";

Regex regex = new Regex(@"^BR\d{4}");
bool doesMatch = regex.IsMatch(matching); // true
doesMatch = regex.IsMatch(notMatching); // false;

Answer 2

BR\d{4}

某些文字至少要回答30个字符：)