我需要一些文本解析帮助（正则表达式/ C＃）

Question

我可以使用适当的正则表达式的一些帮助来解析下面的字符串到3个变量。有评论说// TODO:的部分是我需要正则表达式帮助的地方。现在我刚刚分配了一个静态值，但需要用解析示例文本的真正正则表达式来替换它。谢谢！

// This is what a sample text will look like. 
var text = "Cashpay @username 55 This is a sample message"; 

// We need to parse the text into 3 variables. 
// 1) username - the user the payment will go to. 
// 2) amount - the amount the payment is for. 
// 3) message - an optional message for the payment. 
var username = "username"; // TODO: Get the username value from the text. 
var amount = 55.00; // TODO: Get the amount from the text. 
var message = "This is a sample message"; // TODO: Get the message from the text. 

// now write out the variables 
Console.WriteLine("username: " + username); 
Console.WriteLine("amount: " + amount); 
Console.WriteLine("message: " + message); 

Answer 1

您可以使用捕获组：

var regex = new Regex(@"^Cashpay\s+@([A-Za-z0-9_-]+)\s+(\d+)\s+(.+)$"); 
var text = "Cashpay @username 55 This is a sample message"; 

var match = regex.Match(text); 

if (!match.Success) 
    //Bad string! Waaaah! 

string username = match.Groups[1].Value; 
int amount = int.Parse(match.Groups[2].Value); 
string message = match.Groups[3].Value; 

Answer 2

此方法不执行输入验证;在某些情况下，这可能是好的（例如输入来自已经验证的源）。如果你从用户输入中得到这个，你应该使用一个更健壮的方法。如果是来自可靠来源来，但有多种格式（例如，“Cashpay”是众多选择之一），你可以使用一个开关或者语句拆分后流量控制：

// make sure you validate input (coming from trusted source?) 
// before you parse like this. 

string list[] = text.Split(new char [] {' '}); 

if (list[0] == "Cashpay") 
{ 
    var username = list[1].SubString(1); 
    var amount = list[2]; 
    var message = string.Join(' ',list.Skip(3)); 
} 

或

// make sure you validate input (coming from trusted source?) 
// before you parse like this. 

string list[] = text.Split(new char [] {' '},4); 

if (list[0] == "Cashpay") 
{ 
    var username = list[1].SubString(1); 
    var amount = list[2]; 
    var message = list[3]; 
}