How to check if particular text already exists in a csv file using C#-CodePudding

I want to check if particular text already exists in a csv file.

Is there any way or function except storing the whole file into variable and comparing each of its contents with the target text?

CodePudding user response：

Assuming you don't care about checking for delimiters, etc. and (importantly) you never need to search for text that contains a newline, you could use File.ReadLines and .Contains to check for a specific text:

string fileName = "myFile.csv";
string textToFind = "bob";
bool hasText = File.ReadLines(fileName)
    // .Skip(1) // uncomment this line if your file has a header you wish to skip
    .Any(l => l.Contains(textToFind, StringComparison.Ordinal));

You can change StringComparison.Ordinal to StringComparison.OrdinalIgnoreCase if you want a case insensitive search.

File.ReadLines reads the file line-by-line as .Any is evaluated, so you don't have to load the entire file into memory in one go, and .Any will exit early if a match is found, so the file will stop being read at that point.

Note that for older versions of .NET, .Contains doesn't have an overload that takes a StringComparison so in that case you can only use .Any(l => l.Contains(textToFind));

CodePudding user response：

Just use ReadAllText function and use regex or find to check exist particular text