ansi c fread 16-bit integer and fwrite it as an ascii textfile

Question

I have a binary file that contains 16-bit integer data and i want to convert it to ASCII readable data.

My question is how do I use fread(&buffer,sizeof(buffer) or 16,1,fp); to read the file and use again fwrite(buffer, sizeof(buffer)/7, 1, file); to write the data to a file.

16 in fread is 16-bit and wants to know where it goes or in what form it goes and if in fwrite I will put 7 for 7-bit.

Please provide a code snippet example in C. I want to have the resultant file to be an ordinary readable text file.

Answer 1

You have many things that are confusing.

Assuming buffer is a magically sized properly to fit the file uint8_t array, you can read it in (from a file fopen() ed in binary mode ) using:

fread(buffer, sizeof buffer, in);

That'd give you all of the bits in buffer , if it doesn't fail.

Then, the output is simply:

FILE * const out = fopen("numbers.txt", "wt");
if(out != NULL)
{
  for(size_t i = 0; i < sizeof buffer; i += 2)
  {
    const unsigned int here = buffer[i] + 256 * buffer[i + 1];
    fprintf(out, "%u\n", here);
  }
  fclose(out);
}

This assumes little-endian byte ordering in the binary file. Swap the indexes in the here assignment for big-endian. It also assumes unsigned 16-bit numbers.

Answer 2

after adjusing my code as below the result i get unsigned int,since am expecting data result with alphabetical characters.what additional code can i add to turn it alphabetical?

 #include<stdio.h>
    int main()
       {
    FILE *fp,*out;
  char buffer[256];
          size_t i = 0;
            fp=fopen("c:/Gosam/input.txt", "rb");
            if(out != NULL)
           {
            fread(buffer, sizeof buffer,1, fp);
              }
        out = fopen("c:/Gosam/res.txt", "w");
if(out != NULL)
{
   // buffer = (char*) malloc (sizeof(char)*Size);

  for( i = 0; i < sizeof(buffer); i += 2)
  {
    const unsigned int var = buffer[i] + 256 * buffer[i + 1];
    fprintf(out, "%u\n", var);
  }
  fclose(out);
}
fclose(fp);

}

these are my results but i want to turn them to alphabetical strings.

263
4294966987
4294967222
4294967032
64
4294967013
73
4294967004
90
4294967028
83
4294966975
37
4294966961
5
4294966976
82
4294966942
4294967022
4294966994
11
4294967024
29
4294966985
4294966986
4294966954