Question

我正在尝试写到csv，但是我只将最后一行写到csv，我认为它正在覆盖前一行，因为它在循环语句中，但是我不知道如何使它起作用？生成的csv已成功删除该行中的所有逗号感谢您的协助，因为我是新手，谢谢

private void button1_Click(object sender, EventArgs e) {
    TextFieldParser tfp = new TextFieldParser("C:\\imports\\test1.csv");

    tfp.Delimiters = new string[] { "," };
    tfp.HasFieldsEnclosedInQuotes = true;
    while (!tfp.EndOfData) {

        string[] fields = tfp.ReadFields();

        // remove the commas and double-quotes from the fields.
        for (int i = 0; i < fields.Length; i++)
            fields[i] = fields[i].Replace(",", " ").Replace("\"", "");

        // this is the output
        using (var writer = new System.IO.StreamWriter("c:\\imports\\testing.csv"))
            writer.WriteLine(string.Join(",", fields) + "\n");
    }

    MessageBox.Show("Complete");
    tfp.Close();
}

Answer 1

您的假设是正确的，每次您写新行时，它都会覆盖文件。这是由于每次都打开一个新的StreamWriter引起的，相反，您应该打开一次StreamWriter并继续使用相同的实例，例如：

private void button1_Click(object sender, EventArgs e) {
    TextFieldParser tfp = new TextFieldParser("C:\\imports\\test1.csv");

    tfp.Delimiters = new string[] { "," };
    tfp.HasFieldsEnclosedInQuotes = true;
    using (var writer = new System.IO.StreamWriter("c:\\imports\\testing.csv")) {
        while (!tfp.EndOfData) {

            string[] fields = tfp.ReadFields();

            // remove the commas and double-quotes from the fields.
            for (int i = 0; i < fields.Length; i++)
                fields[i] = fields[i].Replace(",", " ").Replace("\"", "");

            // this is the output
            writer.WriteLine(string.Join(",", fields) + "\n");
        }
    }

    MessageBox.Show("Complete");
    tfp.Close();
}

如您所见，我仅在using循环之前将StreamWriter语句与while一起移动了（并添加了大括号以清楚地表明using的范围声明）。这样，仅创建一个StreamWriter，并且您可以在循环中继续使用它来写入所有行。

读取和写入csv文件并删除逗号

1 个答案: