尝试：

  string  data = File.ReadAllText（path）; 
 data = data.Replace（ ， ，）; 
 File.WriteAllText（路径，数据）; 

忘记数据！ ：doh：[/ edit]

在类似unix的shell（例如，Cygwin）：

perl -pi.bak -es / /， /G; filename_to_process



在命令提示符（DOS shell）中，假设perl.exe的位置在路径上：

perl.exe -pi.bak -es / /，/ g; filename_to_process

应该这样做......

arun 36985
arrunav 25871
elarital 48734
depaal 43212
sujan 23467


my data is up to 2000+ lines it is in notepad as shown in above for that data how can i replace space with comma?
arun,36985
arrunav,25871
elarital,48734
depaal,43212
sujan,23467

Try:

string data = File.ReadAllText(path);
data = data.Replace(" ", ",");
File.WriteAllText(path, data);

[edit]Forgot the data! :doh:[/edit]

At a unix-like shell (e.g., Cygwin):
perl -pi.bak -e "s/ /,/g;" filename_to_process

In a Command Prompt (DOS shell) assuming the location of perl.exe is on the PATH:
perl.exe -pi.bak -e "s/ /,/g;" filename_to_process
ought to do it...