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May 10th, 2012, 06:10 PM
#1
Writing int 10 to a file... what could be easier?
Ok, here is a bug I can't figure out. Say I want to write 256 bytes to a file... say the numbers 0-255. Easy enough. I'm doing it like this.
Code:
ofstream myfile;
int byte_to_write;
char c;
int i;
myfile.open ("Testfile.txt");
byte_to_write = 0;
for(i=0;i<256;i++){
c = byte_to_write & 0xFF; // I realize this is unnecessary for this example
// but in practice sometimes I send values over 255
// and only want to write one byte
myfile.write(&c, 1);
byte_to_write++;
}
myfile.close();
OK, so here is where it gets tricky. Here is the file as it appears in a hex editor:
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
I'll save you the counting and let you know this is 257 bytes, not 256. This is because when byte_to_write = 10, instead of writing 0x0A, 0x0D0A gets written. Only value between 0 and 255 that does this. This same thing happens if I just write "10": 0x0D0A gets written. If you can tell me why, that would be awesome. Thanks.
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