What is a good way to loop through each line of a multiline string without using much more memory (for example without splitting it into an array)?
This question is related to
c#
loops
multilinestring
Sometimes I think we can overcomplicate the solution just to avoid repeating one line of code. This is the reason I landed on this question in the first place.
After thinking about it for a bit I came to the conclusion that the simplest solution is to repeat the ReadLine
before and inside the loop.
using (var stringReader = new StringReader(input))
{
var line = await stringReader.ReadLineAsync();
while (line != null)
{
// do something
line = await stringReader.ReadLineAsync();
}
}
I realize this might be considered to not follow the DRY principle, but I think it's worth considering given the simplicity.
To update this ancient question for .NET 4, there is now a much neater way:
var lines = File.ReadAllLines(filename);
foreach (string line in lines)
{
Console.WriteLine(line);
}
from MSDN for StringReader
string textReaderText = "TextReader is the abstract base " +
"class of StreamReader and StringReader, which read " +
"characters from streams and strings, respectively.\n\n" +
"Create an instance of TextReader to open a text file " +
"for reading a specified range of characters, or to " +
"create a reader based on an existing stream.\n\n" +
"You can also use an instance of TextReader to read " +
"text from a custom backing store using the same " +
"APIs you would use for a string or a stream.\n\n";
Console.WriteLine("Original text:\n\n{0}", textReaderText);
// From textReaderText, create a continuous paragraph
// with two spaces between each sentence.
string aLine, aParagraph = null;
StringReader strReader = new StringReader(textReaderText);
while(true)
{
aLine = strReader.ReadLine();
if(aLine != null)
{
aParagraph = aParagraph + aLine + " ";
}
else
{
aParagraph = aParagraph + "\n";
break;
}
}
Console.WriteLine("Modified text:\n\n{0}", aParagraph);
You can use a StringReader
to read a line at a time:
using (StringReader reader = new StringReader(input))
{
string line = string.Empty;
do
{
line = reader.ReadLine();
if (line != null)
{
// do something with the line
}
} while (line != null);
}
I know this has been answered, but I'd like to add my own answer:
using (var reader = new StringReader(multiLineString))
{
for (string line = reader.ReadLine(); line != null; line = reader.ReadLine())
{
// Do something with the line
}
}
Here's a quick code snippet that will find the first non-empty line in a string:
string line1;
while (
((line1 = sr.ReadLine()) != null) &&
((line1 = line1.Trim()).Length == 0)
)
{ /* Do nothing - just trying to find first non-empty line*/ }
if(line1 == null){ /* Error - no non-empty lines in string */ }
Try using String.Split Method:
string text = @"First line
second line
third line";
foreach (string line in text.Split('\n'))
{
// do something
}
Source: Stackoverflow.com