array initilization.

Posted on 2003-10-22
Last Modified: 2009-12-16
#include <stdio.h>

int main(void) {

int i=0;
int numbers[20];

while(scanf("%d",&numbers[i])!=EOF) i++;

return 0;


// what's wrong in this code...
Question by:xinex
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 10

Expert Comment

ID: 9598365
What error are u facing...........????

Expert Comment

ID: 9598405

Syntax wise, your code has no errors. But it has few logical errors; the while loop in your code should have an extra condition to check for array boundry so that the index 'i' does not go beyond the aray limits, this could be done this way:

      while(i < 20 && scanf("%d", &numbers[i]) != EOF) i++;

I added a check on the value of 'i' so that 'i' will not go beyond the array maximum index which is '19' in your case.
Also, the check on the index is placed before the scanf() function so that it is executed first.

Khalid Omar

LVL 45

Expert Comment

ID: 9598418
scanf  function returns the number of input items assigned
when you try to give EOF, it is assigned to numbers[i] and 1 is returned !! which is not equal to EOF

perhaps you want this

do {
} while (numbers[i-1] != EOF);
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

LVL 45

Expert Comment

by:Kent Olsen
ID: 9600057

Hi Sunnycoder,

I don't think that that is the answer, either.  scanf() returns EOF, it doesn't store EOF as a data value.

The original code should work if the input source is a data file and NOT the keyboard.  This should work fine:

program.exe < DataFile

gets() returns EOF if a lone carriage return is entered from the keyboard.  (Don't use gets()!)  scanf() does not return EOF when input is from the keyboard so other trappings need to occur.


Expert Comment

ID: 9604498
Revised verion of the original code that should not give errors is :

int main(void)
int i=0;
int numbers[20];
while(scanf("%d",&numbers[i]) && i < 20 && numbers[i]!=EOF ) i++;
return 0;

LVL 45

Expert Comment

ID: 9604530
you are right Kent... I shud have read the man page completely

using fgets() might help
LVL 45

Accepted Solution

Kent Olsen earned 20 total points
ID: 9605827

Hi Sunnycoder,

fgets() doesn't return EOF from the keyboard, either.  You'd still have to test for a line-length of zero, which would also mean that blank lines are no longer allowed.

Hi Ajar,

The test "numbers[i]!=EOF" is the same thing that Sunnycoder tripped over.  scanf() won't store EOF at numbers[i] when EOF is encountered.  Since EOF is generally defined to be -1, your loop will exit if scanf() stores a -1.

There needs to be two test cases.  One for keyboard input and one for file input.


Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Have you thought about creating an iPhone application (app), but didn't even know where to get started? Here's how: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Important pre-programming comments: I’ve never tri…
Summary: This tutorial covers some basics of pointer, pointer arithmetic and function pointer. What is a pointer: A pointer is a variable which holds an address. This address might be address of another variable/address of devices/address of fu…
The goal of this video is to provide viewers with basic examples to understand and use pointers in the C programming language.
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use nested-loops in the C programming language.

615 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question