[英]Regex match 2 alpha plus 6 digits in C#
I need a regex
to match this pattern ( using C# ) 我需要一个
regex
来匹配此模式(使用C#)
My match must start with 2 alpha characters ( MA or CA ) and must end with either 6 or seven numeric digits; 我的比赛必须以2个字母字符(MA或CA)开头,并且必须以6或7个数字结尾; such as CA123456 or MA123456 or MA1234567
例如CA123456或MA123456或MA1234567
Here is what I tried: 这是我尝试过的:
Regex.IsMatch(StringInput, @"^[MA]{2}|^[CA]{2}\d{6,7}?"))
Unfortunately, it seems to match most anything 不幸的是,它似乎可以匹配大多数东西
Try this pattern: 试试这个模式:
^[MC]A\d{6,7}$
The leading character class ( [MC]
) requires either an M
or a C
at the start of the string. 前导字符类(
[MC]
)在字符串的开头需要M
或C
Afterwards, \\d{6,7}
matches either 6 or 7 digits. 之后,
\\d{6,7}
匹配6或7位数字。
The issue with your pattern is the first alternative: ^[MA]{2}
matches any string that starts with AA
, AM
, MA
, or MM
. 模式的问题是第一种选择:
^[MA]{2}
匹配任何以AA
, AM
, MA
或MM
开头的字符串。 It doesn't require any following digits at all. 它根本不需要任何以下数字。 Since the regex engine can match the first alternative for a string like AA1234567 (matching the substring AA ), it doesn't even attempt to find another match.
由于正则表达式引擎可以匹配字符串AA1234567的第一个替代项 (匹配子字符串AA ),因此它甚至不会尝试查找其他匹配项。 This is why
这就是为什么
it seems to match most anything.
它似乎可以匹配大多数东西。
I believe there are great usages of RegEx; 我相信RegEx有很多用法。 in this particular case, using the built-in string functions of C# may be a better option:
在这种特殊情况下,使用C#的内置字符串函数可能是一个更好的选择:
This would be the string version based on the above rules: 这将是基于上述规则的字符串版本:
public static bool IsValid( string str )
{
if( str.Length < 8 )
{
return false;
}
if( !str.StartsWith( "CA" ) && !str.StartsWith( "MA" ) )
{
return false;
}
int result;
string end = str.Substring( str.Length - 6 );
bool isValid = int.TryParse( end, out result );
return isValid;
}
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