Code output explanation

Question

Question 1.

#include <stdio.h>
int main(void)
{

  int c;
  while((c=getchar())!='\0')
   {
     putchar(c);
   } 
}

Input

Hello C.

Tell me about you.

Output

Hello C.

Tell me about you.

ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ

and it continues with status-time limit exceeded.

Question 2.

#include <stdio.h>
int main(void)
{
  float a;
  a=46.43253;
  printf("\n%d",a);
  printf("\n%f",a);
  return 0;
}

Output

536870912

46.432529

Ask ***one*** question, not two unrelated ones. Please do not add a third question, ask a new one. — Weather Vane, Nov 23 '16 at 19:29
Try using `\n` instead of `\0`. It's better practice to use new line character than null terminator. — Imtiaz Raqib, Nov 23 '16 at 19:34
`a=46.43253;` This is not Right. What is `a` and what is `46.43253` ? — Michi, Nov 23 '16 at 19:44

score 3 · Accepted Answer · edited Jun 20 '20 at 09:12

3

Output- 536870912

46.432529

In general using incorrect format specifier triggers undefined behavior - which is what you have when you use %d in printf for printing float. In this case, you can expect any output usually.

However, it may also be the case that since you have specified to read the float number as integer (e.g. by using %d specifier), it simply interpreted the result as integer - hence the strange number (since floats and integers are stored differently).

If you are interested why the second printf prints a number slightly different from yours, this may help you.

edited Jun 20 '20 at 09:12

Community

1
1

answered Nov 23 '16 at 19:20

Giorgi Moniava

27,046
9
53
90

`a=46.43253;` This is not right because `a` is FLOAT. What is `46.43253` ? – Michi Nov 23 '16 at 19:43
1

@Michi Sorry? didn't follow you. – Giorgi Moniava Nov 23 '16 at 19:50
@Michi Are you saying `46.43253` is not a float? – Imtiaz Raqib Nov 23 '16 at 20:43
What's the difference between 46.43253 and 46.43253f? – Michi Nov 24 '16 at 05:04

score 0 · Answer 2 · answered Nov 23 '16 at 20:10

This block is fine:

float a;
a=46.43253;

This block is also fine:

printf("\n%f",a);

The problem is with this block:

printf("\n%d",a);

Particularly this part:

"\n%d"

Please keep in mind you declared a float and using the integer syntax to output it. That's why you are getting the negative output If it is a case where you don't want to change the "%d," then simply cast it as a float before output

Code output explanation

2 Answers2