C program reads one char at a time, but never reaches EOF?

Question

I'm writing a program that needs to read input one character at a time and transform that input, and I need to be able to differentiate the end of a line (\n) and the end of the stdin. For whatever reason my program just loops infinitely after it gets to the last line and never prints it. I'm wondering why it's never catching EOF? I took out some of the code from the bottom because it's just a ton of if statements replacing characters with uppercase characters and such. I basically just don't understand why my code is never breaking.

#include <stdio.h>
#include <string.h>

int main(void)
{
  int MAXCHARS = 79;
  int curr;
  char currline[MAXCHARS*2];
  char lastline[MAXCHARS*2];

  memset(currline,0,158);
  memset(lastline,0,158);

  int pointer = 0;

  while (1)
  {
    curr = getchar();

    if (curr == EOF)
    {
      for (int i = 0; i < pointer; i++)
        {
          printf("%c", currline[i]);
        }
      break;
    }

    if (curr == '\n')
    {
      if (currline == lastline) 
      {
        pointer = 0;
      }
      else
      {
        strcpy(lastline,currline);
        for (int i = 0; i < pointer; i++)
        {
          printf("%c", currline[i]);
        }

        pointer = 0;
      }
    }

  }

}

this `currline == lastline` doesnt do what you think. If you want to compare the strings you must use `strcmp` — pm100, May 01 '18 at 00:26
also the pointer loop after your EOF test will never do anything. pointer is always 0 at that point — pm100, May 01 '18 at 00:28
Ya the pointer is increased in the code I left out. Didn't know about strcmp though. Thanks! — Ethan Burke, May 01 '18 at 00:42
I was able to run the program and it quit after EOF as expected. You can try it [here](https://onlinegdb.com/SyliwYS6f). Press Ctrl+D to simulate EOF — Increasingly Idiotic, May 01 '18 at 06:22

score 0 · Answer 1 · answered May 01 '18 at 00:38

0

As far as I can understand, your program never reaches that block of code, because it never gets EOF. Try Ctrl+Z for Windows or Ctrl+D for Linux.

Also see https://en.wikipedia.org/wiki/End-of-file and What is considered as EOF in stdin?

answered May 01 '18 at 00:38

icydemon

78
1
9

C program reads one char at a time, but never reaches EOF?

1 Answers1