Strange 0x0D being added to my binary file

Question

I have this strange problem:

I write 16 chars to a binary file and then I write 3 integers but when I open my file with some binary file viewer, I see an extra byte is added (which equals 0x0D).

Here's my code:

for(i = 0; i < 16; i++)
{
    if(i < strlen(inputStr))
    {
        myCharBuf[0] = inputStr[i];
    }
    else
    {
        myCharBuf[0] = 0;
    }

    fwrite(myCharBuf, sizeof(char), 1, myFile);
}

myIntBuf[0] = inputNumber1;

fwrite(myIntBuf, sizeof(int), 1 ,myFile);

myIntBuf[0] = inputNumber2;

fwrite(myIntBuf, sizeof(int), 1 ,myFile);

myIntBuf[0] = inputNumber3;

fwrite(myIntBuf, sizeof(int), 1 ,myFile);

I get the following byte-values:

61 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0D 0A 00 00 00 05 00 00 00 08 00 00 00

When I expect:

61 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0A 00 00 00 05 00 00 00 08 00 00 00

Does anyone have an idea why it might happen?

Answer 1

0A is the line feed character and 0D is the carriage return. These are usually associated with text mode.

Have you opened the file in binary mode? (e.g. fopen("foo.txt", "wb"))