Getting count of first character in a text file?

user_3266638 0
Viewed 137

I have a large text file that looks like this where there is one row with an A at the beginning and one C at the end and an x number of B's in between:

A

B

B

B

C

What's the best way to get a number count for the number of times A, B, or C appear? All of these rows have more data but this is what I'm trying to achieve.

Do I have to read in the whole file or is reading it one line at a time the best?

.net c#
3 Answers

I think something like that would work

foreach (var grouping in File.ReadAllLines("<file-path-here>").GroupBy(x => x[0]))
{
    Console.WriteLine($"char: {grouping.Key}, count: {grouping.Count()}");
}
user_106474920

The below snippet of code is a easy implementation: 

 int iBCount = File.ReadAllLines(filePath).Count -2;
 int iACount = 1; // We already knew this
 int iCCount = 1; // We already knew this

Also, if you know size in bytes of each line (they must be the same for each line) and you are concerned with the performance then you can simply calculate the number of "B" lines as follows

 // There will be no problem with typecast if each lines is the same length in bytes
 int iBLines = (int)(new System.IO.FileInfo(pathToFile).Length / FIXED_LINE_SIZE_IN_BYTES);
user_115512380 
string [] lines = File.ReadAllLines(filePath)

int A_count = 0, B_count = 0, C_count = 0;
foreach (string line in lines)
{
    switch(line[0])
    {
        case 'A':
            A_count++;
            break;
        case 'B':
            B_count++;
            break;
        case 'C':
            C_count++;
    }
}
user_116112950
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