Question

无法弄清楚如何防止数组中的最后一个键没有逗号。由于它被导出到.Json文件，因此最后一个键不应该有“，”。

我知道你可以使用.Last();来检测它，但我似乎无法做到这一点。有什么建议吗？

//Data Path
string dataPath = @"..\..\FileIOExtraFiles\DataFieldsLayout.txt";
string[] dataList = File.ReadAllLines(dataPath);
//save Data data

using (StreamWriter outStream = new StreamWriter(outputFolder + @"\CharacterStringData3.json"))
{
    outStream.WriteLine("{");
    for (int i = 0; i < dataFile.Length; i++)
    {
        string s = dataFile[i];
        char last = s.Last();
        if (s == "")
        {
            outStream.WriteLine("\"" + dataList[i] + "\"" + " : " + "\" \",");
        }
        else
        {
            outStream.WriteLine("\"" + dataList[i] + "\"" + " : \"" + s + "\",");
        }
    }
    outStream.WriteLine("}");
}

输出：

{
 "data1":"item1",
 "data2":item2",
 "lastKey":item3",//trying to remove comma from last key in array.
}

Answer 1

正如其他人所指出的那样，手动构建json是没有意义的，但考虑到这是一个更多关于技术的问题，这里有一种方法：你可以改成它：

Video

后缀将用于除最后一次之外的每次迭代。

Answer 2

更改此

library(dplyr)

result <- DT %>%
    group_by(town,tc) %>%
    mutate_each(funs(mean,sd,
                     uplimit = (mean(.) + 1.96*sd(.)),
                     lowlimit = (mean(.) - 1.96*sd(.)),
                     Aoutlier = as.integer(. >= mean(.) - 1.96*sd(.) &
                                               . <= mean(.) - 1.96*sd(.))),
                -town,-tc)

到此

outStream.WriteLine("\"" + dataList[i] + "\"" + " : " + "\" \",");

Answer 3

不是在每一步使用outStream.WriteLine()，而是将其存储在字符串中。然后，您可以从该字符串中删除最后一个逗号并立即写入整个字符串：

//Get last index of comma
int lastCommaIndex = outputString.LastIndexOf(',');

//Create new StringBuilder with everything before the last comma
StringBuilder sb = new StringBuilder(outputString.Substring(0,lastCommaIndex));

//Add everything after the last comma, or just add a closing brace
//sb.Append("}"); //This instead of next line
sb.Append(outputString.Substring(lastCommaIndex+1));

//Add contents of StringBuilder to the Stream
outSteam.WriteLine(sb);

防止字符串中的最后一个键有逗号

3 个答案: