Comparing unsigned char and EOF

Question

when the following code is compiled it goes into an infinite loop:

int main()
{
    unsigned char  ch;
    FILE *fp;
    fp = fopen(\"abc\",\"r\");
    if(fp         


        

Answer 1

I have encountered this problem too. My solution is to use feof().

unsigned int xxFunc(){
  FILE *fin;
  unsigned char c;
  fin = fopen("...", "rb");
  if(feof(fin) != 0) return EOF;
  c = fgetc(fin);
  fclose(fin);
...
}

And you can define an int variable to compare with EOF. For example:

int flag = xxFunc();
while(flag != EOF) {...}

This works for me.

**IMPORTANT UPDATE***

After using the method I mentioned before, I found a serious problem. feof() is not a good way to break the while loop. Here is the reason for it. http://www.gidnetwork.com/b-58.html

So I find a better way to do this. I use an int variable to do it. here:

int flag;
unsigned char c;
while((flag = fgetc(fin)) != EOF) 
{ 
  //so, you are using flag to receive, but transfer the value to c later.
  c = flag;
  ... 
}

After my test, this works.