Question

How do I parse the size of a file from like 1024 to 1kb?
once I created a function for it which was like 30 lines long full of if’s.
is there a more ‘elegant’ way to do it?
and what do I need to use?
1kb = 1000b or 1kb = 1024b?

Answer 1

This solution doesn’t look unreasonable. It’s a little long, but it does cater for exa/petabytes!

C# Human-Readable File Size Function

// Returns the human-readable file size for an arbitrary, 64-bit file size
//  The default format is "0.### XB", e.g. "4.2 KB" or "1.434 GB"
public static string GetSizeReadable(long i)
{
    string sign = (i < 0 ? "-" : "");
    double readable = (i < 0 ? -i : i);
    string suffix;
    if (i >= 0x1000000000000000) // Exabyte
    {
        suffix = "EB";
        readable = (double)(i >> 50);
    }
    else if (i >= 0x4000000000000) // Petabyte
    {
        suffix = "PB";
        readable = (double)(i >> 40);
    }
    else if (i >= 0x10000000000) // Terabyte
    {
        suffix = "TB";
        readable = (double)(i >> 30);
    }
    else if (i >= 0x40000000) // Gigabyte
    {
        suffix = "GB";
        readable = (double)(i >> 20);
    }
    else if (i >= 0x100000) // Megabyte
    {
        suffix = "MB";
        readable = (double)(i >> 10);
    }
    else if (i >= 0x400) // Kilobyte
    {
        suffix = "KB";
        readable = (double)i;
    }
    else
    {
        return i.ToString(sign + "0 B"); // Byte
    }
    readable = readable / 1024;

    return sign + readable.ToString("0.### ") + suffix;
}

Sample Usage

It is recommended to put the above function in a helper or utility class as a public static method.

// EXAMPLE OUTPUT
GetSizeReadable(1023); // 1023 B
GetSizeReadable(1024); // 1 KB
GetSizeReadable(1025); // 1.001 KB

// Example of getting a file size and converting it to a readable value
string fileName = "abc.txt";
long fileSize = new System.IO.FileInfo(fileName).Length;
string sizeReadable = GetSizeReadable(fileSize);