CODEWITHSUNDEEP
c#splitstreamreaderreadline
Remotejon
Remotejon

Reputation: 35

Attempting to read a txt file - locking up

I am trying to read a certain part of textfile. The text looks like the following:

[HRZones]
195
175
156

0

[SwapTimes]

[Trip]
474
0
6616
-223


[HRData]
84  182 87  -222    129 4139
84  182 87  -222    129 4139
88  179 86  -222    133 3640
95  185 92  -222    136 3393
103 193 91  -222    123 4666
107 196 94  -222    125 5684
107 198 96  -222    128 4919
109 197 95  -222    131 4926
110 198 96  -222    134 4655
111 196 95  -222    126 4154

The file actually contains a lot more lines under the [HRData] section.

I am trying to grab the [HRData} using the following code. Sadly, this locks up the program; a breakpoint shows this happens in the first while loop.. almost like it can't see anything? 

 private void readFile()
    {
        //read the hrm file and split values
        try
        {
            using (StreamReader sr = new StreamReader(file_name))
            {
                string line;

                while ((line = sr.ReadLine()) != "[HRData]")
                {
                    line = sr.ReadLine(); // FAILS HERE.. 
                }

                while((line = sr.ReadLine()) != null)
                {
                    string split = line;
                    string[] values = split.Split('\t');
                    foreach (String value in values)
                    {
                        hrdata[i, j] = int.Parse(value);
                        i++;
                        if (i > 5)
                        {
                            i = 0;
                            j++;
                        }
                    }
                }
            }
        }

The file_name is being passed from a previous check and the data seems good.

Upvotes: 0

Views: 199

Answers (5)

Steve
Steve

Reputation: 216343

With that loop you risk to jump past the line that contains your searched text because you read a line two time but test only one time

 string line = sr.ReadLine();
 while (line != null && line != "[HRData]")
 {
     line = sr.ReadLine();
 }

If the file happens to have one more line before the loop probably it would have worked but the bug is still there

Upvotes: 0

Atif Aziz
Atif Aziz

Reputation: 36648

As some have already pointed out, you're reading a line during the loop condition and then again in the body of the loop so this could work or fail depending on whether [HRData] appears on an odd or an even line of the file.

Re-write the while loop as a for one instead:

for (var line = sr.ReadLine();
     line != null && line != "[HRData]");
     line = sr.ReadLine()) { /* NOP */ }

And if you can afford to use LINQ, then the following is even simpler and doesn't require any brain gymnastics:

foreach (var line in File.ReadLines().SkipWhile(s => s != "[HRData]")) {
    // ...
}

Upvotes: 1

loopedcode
loopedcode

Reputation: 4893

Check for EOF and Trim() it to make text equality to work. Following should work

            while (!sr.EndOfStream)
            {
                var line = sr.ReadLine();
                if (!string.IsNullOrWhiteSpace(line) && line.Trim() == "[HRData]")
                {
                    break;
                }
            }

            while (!sr.EndOfStream)
            {
                string split = sr.ReadLine();
                string[] values = split.Split('\t');

                foreach (String value in values)
                {
                    hrdata[i, j] = int.Parse(value);
                    i++;
                    if (i > 5)
                    {
                        i = 0;
                        j++;
                    }
                }
            }

Upvotes: 1

bubbinator
bubbinator

Reputation: 495

2 things I noticed:

1) You have no check for the [HRData] "tag". You check for the line not being the tag and not null.

2) I think you while loops as a whole do not know to stop reading at the end of the file.

Upvotes: 0

AlexD
AlexD

Reputation: 32596

Here you check one line and skip the next one. Avoid second ReadLine.

while ((line = sr.ReadLine()) != "[HRData]")
{
    line = sr.ReadLine(); // FAILS HERE.. 
}

Upvotes: 2

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