C程序停止接受1023个字符的输入

Question

I'm teaching myself C using K&R. Exercise 1-16 asks me to refactor some provided code to give the length of "arbitrarily long input lines".

Whilst working on the problem I found that my terminal ceases to accept input after 1023 characters; a very suspicious number I'm sure you'll agree!! I have tested on Mac OS X and OpenBSD and see the same behaviour. The program hasn't stopped responding because typing backspace and submitting the input works correctly.

I couldn't figure out how to debug this with gdb because the problem occurs during data entry, not after submission when stepping through with gdb.

I could see no reference to a limit in the getchar or bash manpages, and indeed it seems very little input anyway.

I reduced the problem to the following and see the same behaviour.

#include <stdio.h>

main()
{
  int c,i=0;

  while ((c=getchar()) != EOF && c!='\n')
    ++i;
  printf("%d\n",i);

  return 0;
}

Could people please explain:

1. Why this is happening
2. How I might debug this kind of issue myself

Many thanks.

Answer 1

As per the comments on my question, it would appear to be a terminal limitation. Piping a file into the program works as expected.