获取货币汇率 [英] Get currency rate

问题描述

我想做的是，

• 从该网站获得转化率(我选择了 xe.com因为它支持所需的货币 AZN <-> USD)
• 例如，如果可以发送5 AZN"并获得它等于美元的金额.URL 如下所示:http://www.xe.com/ucc/convert/?Amount=5&From=AZN&To=USD

我从博客:

string xeString = String.Format("http://www.xe.com/ucc/convert.cgi?Amount=1&From={0}&To={1}", srcCurrency, dstCurrency);
System.Net.WebRequest wreq = System.Net.WebRequest.Create(new Uri(xeString));
System.Net.WebResponse wresp = wreq.GetResponse();
Stream respstr = wresp.GetResponseStream();
int read = respstr.Read(buf, 0, BUFFER_SIZE);
result = Encoding.ASCII.GetString(buf, 0, read);

现在，这将返回类似于 XE.com: USD to EUR rate: 1.00 USD = 0.716372 EUR

Now, this will return something like XE.com: USD to EUR rate: 1.00 USD = 0.716372 EUR

问题是:

1. 我不知道变量 buf 和 BUFFER_SIZE 是什么.
2. 如何获得准确的结果，例如发送 5 AZN 并以美元获得结果(双倍)?http://www.xe.com/ucc/convert/?Amount=5&From=AZN&To=USD

1. I have no idea what the variables buf and BUFFER_SIZE are.
2. How can I get an exact result, for instance send 5 AZN and get the result in USD (as double)? http://www.xe.com/ucc/convert/?Amount=5&From=AZN&To=USD

推荐答案

1. http://msdn.microsoft.com/fr-fr/library/system.io.stream.read.aspx

buf 是一个 byte[] 数组，一旦方法返回，其中包含您刚刚读取的数据.BUFFER_SIZE 是您要读取的数据的大小.如果要读取单个字节，则 BUFFER_SIZE=1.如果要读取一千字节的数据，BUFFER_SIZE=1024等.注意，如果你要求一个太大的缓冲区(例如，当数据为1KB时要求1MB)，它不会有太大关系.它将读取一个 KB，然后返回.

buf is a byte[] array, which, once the method has returned, contains the data that you just Read. BUFFER_SIZE is the size of the data you want to read. If you want to read a single byte, BUFFER_SIZE=1. If you want to read one kilobyte of data, BUFFER_SIZE=1024, etc. Note that, if you ask for a too big buffer (e.g. asking for 1MB when the data is 1KB), it won't matter much. It will read a KB, and return.

您的最终字符串应如下所示，除非 XE.com 决定更改它:

Your final string should look like this, unless XE.com decides to change it:

XE.com:美元兑欧元汇率:1.00 美元 = 0.716372 欧元

XE.com: USD to EUR rate: 1.00 USD = 0.716372 EUR

您可以使用 String 方法去除不需要的东西:整个第一部分

You can use the String methods to strip things you don't need: The whole first part

(XE.com:美元兑欧元汇率:)

只需使用您的数据构建一个字符串即可轻松删除:

can be easily removed by just building a string with your data:

(string header = "XE.com: {0} to {1} rate:",currency1,currency2)

，然后调用String.Replace(header, '').从那里，您可以调用 String.Split('=')，在 '=' 符号处拆分，然后从拆分的字符串中删除货币部分(同样，String.Replace()) 最后调用 Double.TryParse()

,then calling String.Replace(header, ''). From there, you can call String.Split('='), splitting at the '=' sign, then removing the currency part from the splitted strings (again, String.Replace()) and finally calling Double.TryParse()

注意:codesparkle 的方法更简单，因为你基本上跳过了第 1 步.但是 XE.com 没有提供 API:你不能保证返回的字符串是有效的，或者将来某天不会改变.

Note: codesparkle's method is way easier, because you basically skip step 1. But XE.com are not providing an API: You have no guarantee the returned string will be valid, or won't change someday in the future.

好的，这是一些代码:

private double GetConvertedCurrencyValue(string inputCurrency, string outputCurrency, double value) 
{
    string request = String.Format(http://www.xe.com/ucc/convert.cgi?Amount={0}&From={1}&To={2}", value, inputCurrency, outputCurrency);

    System.Net.WebClient wc = new System.Net.WebClient();
    string apiResponse = wc.DownloadString(request);    // This is a blocking operation.
    wc.Dispose();

    /* Formatting */
    // Typical response: "XE.com: curr1 to curr2 rate: x curr1 = y curr2"
    // The first part, up until "x curr1" is basically a constant
    string header = String.Format("XE.com: {0} to {2} rate:" inputCurrency, outputCurrency);

    // Removing the header
    // The response now looks like this: x curr1 = y curr2
    apiResponse = apiResponse.Replace(header, "");

    // Let's split the response at '=', to retrieve the right part
    string outValue = apiResponse.Split('=')[1];

    // Getting rid of the 'curr2' part
    outValue = outValue.Replace(outputCurrency, "");

    return Double.Parse(outValue, System.Globalization.CultureInfo.InvariantCulture);
}

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