Using StreamReader to check if a file contains a string

Question

I have a string that is args[0].

Here is my code so far:

static void Main(string[] args) {     string latestversion = args[0];     // create reader & open file     using (StreamReader sr = new StreamReader("C:\\Work\\list.txt"))     {         while (sr.Peek() >= 0)         {             // code here         }    } } 

I would like to check if my list.txt file contains args[0]. If it does, then I will create another process StreamWriter to write a string 1 or 0 into the file. How do I do this?

Answer 1

Are you expecting the file to be particularly big? If not, the simplest way of doing it would be to just read the whole thing:

using (StreamReader sr = new StreamReader("C:\\Work\\list.txt")) {     string contents = sr.ReadToEnd();     if (contents.Contains(args[0]))     {         // ...     } } 

Or:

string contents = File.ReadAllText("C:\\Work\\list.txt"); if (contents.Contains(args[0])) {     // ... } 

Alternatively, you could read it line by line:

foreach (string line in File.ReadLines("C:\\Work\\list.txt")) {     if (line.Contains(args[0]))     {         // ...         // Break if you don't need to do anything else     } } 

Or even more LINQ-like:

if (File.ReadLines("C:\\Work\\list.txt").Any(line => line.Contains(args[0]))) {     ...  } 

Note that ReadLines is only available from .NET 4, but you could reasonably easily call TextReader.ReadLine in a loop yourself instead.

Answer 2

1. You should not add the ';' at the end of the using statement.

2. Code to work:

   string latestversion = args[0];  using (StreamReader sr = new StreamReader("C:\\Work\\list.txt")) using (StreamWriter sw = new StreamWriter("C:\\Work\\otherFile.txt")) {         // loop by lines - for big files         string line = sr.ReadLine();         bool flag = false;         while (line != null)         {             if (line.IndexOf(latestversion) > -1)             {                 flag = true;                 break;             }             line = sr.ReadLine();         }         if (flag)             sw.Write("1");         else             sw.Write("0");          // other solution - for small files         var fileContents = sr.ReadToEnd();         {             if (fileContents.IndexOf(latestversion) > -1)                 sw.Write("1");             else                 sw.Write("0");         } }