reading a binary unknown size file in c#

Question

I have just switched to c# from c++. I have already done some task in c++ and the same now i have to translate in c#.

I am going through some problems.

I have to find the frequency of symbols in binary files (which is taken as sole argument, so don't know it's size/length).(these frequency will be further used to create huffman tree).

My code to do that in c++ is below :

My structure is like this:

struct Node     
{    
    unsigned int symbol;
    int freq;    
    struct Node * next,  * left, * right;  
};
Node * tree;

And how i read the file is like this :

FILE * fp;
fp = fopen(argv, "rb");
ch = fgetc(fp);

while (fread( & ch, sizeof(ch), 1, fp)) {
    create_frequency(ch);
}

fclose(fp);

Could any one please help me in translating the same in c# (specially this binary file read procedure to create frequency of symbols and storing in linked list)? Thanks for the help

Edit: Tried to write the code according to what Henk Holterman explained below but still there is error and the error is :

error CS1501: No overload for method 'Open' takes '1' arguments
/usr/lib/mono/2.0/mscorlib.dll (Location of the symbol related to previous error)
shekhar_c#.cs(22,32): error CS0825: The contextual keyword 'var' may only appear within a local variable declaration
Compilation failed: 2 error(s), 0 warnings

And my code to do this is:

static void Main(string[] args)
{
    // using provides exception-safe closing
    using (var fp = System.IO.File.Open(args))
    {
        int b; // note: not a byte
        while ((b = fp.Readbyte()) >= 0)
        {
            byte ch = (byte) b;
            // now use the byte in 'ch'
            //create_frequency(ch);
        }
    }
 }

And the line corresponding to the two errors is :

using (var fp = System.IO.File.Open(args))

could some one please help me ? I am beginner to c#

Answer 1

string fileName = ...
using (var fp = System.IO.File.OpenRead(fileName)) // using provides exception-safe closing
{
    int b; // note: not a byte

    while ((b = fp.ReadByte()) >= 0)
    {
        byte ch = (byte) b;
        // now use the byte in 'ch'
        create_frequency(ch);
    }
}