c＃智能方法删除字符串中多个字符的出现

Question

My program reads a file which has thousands of lines of something like this below "Timestamp","LiveStandby","Total1","Total2","Total3", etc.. each line is different What is the best way to split by , and delete the "" as well as put the values in a list

this is what I have

 while ((line = file.ReadLine()) != null)
  {
     List<string> title_list = new List<string>(line.Split(',')); 
  }

the step above still missing the deletion of the quotes. I can do foreach but that kinda defeat the purpose of having List and Split in just 1 line. What is the best and smart way to do it?

Answer 1

The best way in my opinion is to use a library that parses CSV , such as FileHelpers .

Concretely, in your case, this would be the solution using the FileHelpers library:

Define a class that describes the structure of a record:

[DelimitedRecord(",")]
public class MyDataRecord
{
    [FieldQuoted('"')]
    public string TimeStamp;
    [FieldQuoted('"')]
    public string LiveStandby;
    [FieldQuoted('"')]
    public string Total1;
    [FieldQuoted('"')]
    public string Total2;
    [FieldQuoted('"')]
    public string Total3;
}

Use this code to parse the entire file:

var csvEngine = new FileHelperEngine<MyDataRecord>(Encoding.UTF8)
    { 
        Options = { IgnoreFirstLines = 1, IgnoreEmptyLines = true }
    };

var parsedItems = csvEngine.ReadFile(@"D:\myfile.csv");

Please note that this code is for illustration only and I have not compiled/run it. However, the library is pretty straightforward to use and there are good examples and documentation on the website.

Answer 2

I'm going to clarify this a bit. If you have a user formatted file that has a predictable format (ie the user has generated the data out of EXCEL or similar program) then you are way better off using an exising parser that is well tested.

Scenarios like the following are just a few examples that manual parsing will have problems with:

"column 1", 2, 0104400, $1,300, "This is an interestion question, he said"

.. and there are more with escaping, file formats etc that can be a headache for roll your own.

If you do that, then ensure you get one that can tollerate differences in columns per row as it can make a difference.

If, on the other hand, you know what's going into the data which is common in system generated files then using CSV parsers will cause more problems than they solve. For example, I have dealt with scenarios where the first part is fixed and can be strongly typed, but there are following parts in a row that are not. This can also happen if you're parsing flat file data in fixed width scenarios from legacy databases. A csv solution makes assumptions we don't want and is not the right solution in many of those cases.

If that is the case and you just want to strip out quotes after splitting on commas, then try a bit of linq. This can also be extended to replace specific characters you are worried about.

line.Split(',').Select(i => i.Replace("\"", "")).ToArray()

Hope that clears up all the conflicting advice.

Answer 3

Keeping it simple like this should work:

List<string> strings = new List<string>();
while ((line = file.ReadLine()) != null) 
    string.AddRange(line.Replace("\"").split(',').AsEnumerable());

Answer 4

You can use the Array.ConvertAll() function.

string line = "\"Timestamp\",\"LiveStandby\",\"Total1\",\"Total2\",\"Total3\"";

var list = new List<String>(Array.ConvertAll(line.Split(','), x=> x.Replace("\"","")));

Answer 5

Perform the Replace first, then Split into your List. Here's your code with Replace.

while ((line = file.ReadLine()) != null)   
{      
  List<string> title_list = new List<string>(line.Replace("\"", "").Split(','));    
}

Although, you're going to need a variable to hold all of the Lists, so look at using AddRange().