Uninitialized char variable

Question

When compiling my code below, it says that f is uninitialized. How do I initialize a character and why do I need to? My intention is to end the loop when f is entered and stored in c.

#include <stdio.h>
#include <string.h>
int main(void)
{
  int count= 0;
  char c,f;

  printf("Input a character:\n");
  do
  {
    c = getchar();
    count++
  }while(c!=f);
  printf("number of characters: %d", count);
  return 0;
}

If you don't initialize it, what are you expecting `c!=f` to compare with? — Barmar, Oct 20 '17 at 21:35
`f = 'E'` will resolve the issue, you have to set value of variable `f` — Mr.Nimelo, Oct 20 '17 at 21:36
Your question has never been [accepted](https://stackoverflow.com/help/accepted-answer) before. — BLUEPIXY, Oct 20 '17 at 21:39
[The return value of `getchar` must be stored into an `int`](https://stackoverflow.com/q/35356322/918959). — Antti Haapala -- Слава Україні, Oct 20 '17 at 23:04

score 3 · Answer 1 · answered Oct 20 '17 at 21:37

3

f is the name of the variable not the character 'f' !

you need to initialize char f = 'f';

answered Oct 20 '17 at 21:37

fievel

480
3
9

Cheers, it worked! – oxodo Oct 20 '17 at 21:47

score 2 · Answer 2 · answered Oct 20 '17 at 21:37

You need to initialize the variable, because otherwise c != f is comparing c with whatever indeterminate value happens to be in the f variable.

If you want to test whether they typed the letter f, you should be comparing with a literal, not a variable.

do {
    c = getchar();
    count++;
} while (c != 'f');

score 0 · Answer 3 · 2017-10-21T00:26:19.200

How do I initialize a character?

You does not initialize a character, you initialize a variable.

And why do I need to?

When you declare a local variable, this variable are allocated on the stack and it's value is the current value into that position at the stack (i.e. garbage).

So you need to set a value to that variable to avoid a undefined behavior of the program. In your specif case this value is: 'f'. The single quotes means that f is a character, this is the type of data that your variable (char) expects.

Uninitialized char variable

3 Answers3