急!!读取文本文件的问题,在线等!!

Question

一个文本文件里有很多负数,如何把这些负数找出来并替换为零:
1.24124  2.424124   3.1414  -123.42 ...
2.24124  -2.42412   2.31314  231.42 ...
-3.4154  1.422124   2.31314  31.422 ...
...
...
...
...这个文本很大,如何用程序实现快速查找并替换,麻烦给个程序实例!谢谢!!

Answer 1

string text = "1.24124 2.424124 3.1414 -123.42 2.24124 -2.42412 2.31314 231.42";
string aa = "";
string[] arr = text.Split(' ');
for(int i=0;i<arr.Length;i++)
{
    if(i==0)
    {
if(arr[i].IndexOf("-")>=0)
{
    arr[i] = "0";
}
aa = arr[i];
     }
      else
     {
if(arr[i].IndexOf("-")>=0)
{
arr[i] = "0";
}
     aa += ","+arr[i];
}
     }
Response.Write(aa);

Answer 2

*.txt 里面的内容如下:
1.24124  2.424124  3.1414  -123.42 ... 
2.24124  -2.42412  2.31314  231.42 ... 
-3.4154  1.422124  2.31314  31.422 ... 
... 
... 
... 
... 
如何用程序实现快速查找负数并替换为零,麻烦给个详细一点的程序!替换后的仍然保存在*.txt中

Answer 3

给个示例代码，效率如何不太清楚，功能应该能实现private void button1_Click(object sender, EventArgs e)
        {
            String result = String.Empty;
            using (StreamReader reader = new StreamReader(@"C:\1.txt"))
            {
                String line = null;
                while ((line = reader.ReadLine()) != null)
                {
                    result += ReplaceMinusNumber(line);
                    result += System.Environment.NewLine;
                }
                reader.Close();
            }            using (StreamWriter writer = new StreamWriter(@"C:\1.txt"))
            {
                writer.Write(result);
                writer.Close();
            }
        }private String ReplaceMinusNumber(string line)
        {
            String result = String.Empty;
            String[] numbers = line.Split(' ');
            for (int i = 0; i < numbers.Length; i++)
            {
                if (numbers[i].StartsWith("-"))
                {
                    result += "0 ";
                    continue;
                }
                result += numbers[i] + " ";
            }            return result;
        }

Answer 4

按照LorenLiu 的代码做  没有错！  保证能够实现你的功能！ 

Answer 5

        private void button1_Click(object sender, EventArgs e)
        {
            string fs = File.ReadAllText("myfile.txt");
            fs=Regex.Replace(fs, @"-(\d)+.(\d)*", "0",RegexOptions.Multiline );
            File.WriteAllText("myfile.txt", fs);
        }