Question

When I try to read integers from a file, the code ends up reading different numbers than expected.

The data file contains the following numbers:

1111 111 222 333 444 555 666 777 888 -1

When I read the file, it returns the following numbers:

825307441   825307424   842150432   858993440   875836448
892679456   909522464   926365472   943208480   170994976

Why is this happening?

Relevant code:

/* A file named data contains some integer numbers.write a program to
   read these numbers and store the odd numbers in one file and store 
   the even numbers in file.*/

  int main()
  {
    FILE *fp1,*fp2,*fp3;
    int number;

    fp1=fopen("DATA","r");
    fp2=fopen("even","w");
    fp3=fopen("odd","w");

    printf("numbers in  file are\n");
    while((number=getw(fp1))!=EOF)
    {
      printf("%d\t",number);
    }
    fclose(fp1);
    fp1=fopen("DATA","r");


    while((number=getw(fp1))!=EOF)
    {
      if((number%2)==0)
      {
        putw(number,fp2);
      }
      else
      {
        putw(number,fp3);
      }
    }
    fclose(fp1);
    fclose(fp2);
    fclose(fp3);

    fp2=fopen("even","r");
    fp3=fopen("odd","r");

    printf("\nnumbers in even file are\n");
    while((number=getw(fp2))!=EOF)
    {
      printf("%d\t",number);
    }

    printf("\nnumbers in odd file are\n");
    while((number=getw(fp3))!=EOF)
    {
      printf("%d\t",number);
    }
    fclose(fp2);
    fclose(fp3);
    return 0;

  }

Answer 1

You are reading numbers represented in plain text.

getw reads a machine word (say 8 bytes on my 64-bit box for example), and when you write it out, it writes that out. This is not what you want.

Use fscanf instead of getw to read formatted values.