我需要一些文本解析帮助（正则表达式/C#）

Question

我可以使用一些正确的正则表达式帮助将以下字符串解析为 3 个变量。 cmets 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实正则表达式替换它。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

此方法不进行输入验证；在某些情况下，这可能没问题（例如，输入来自已经过验证的来源）。如果您从用户输入中获取此信息，您可能应该使用更强大的方法。如果它来自受信任的来源但有多种格式（例如“现金支付”是众多选择之一），您可以在拆分后使用 switch 或 if 语句进行流量控制：

// 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];
}