Thread: EOF end input

Original assignment: "A user should be able to enter up to 200 items of float data. The program should calculate the number of items in the data. The symbol <EOF> in the sample run below should be replaced with CTRL-Z or CTRL-D or the end-of-file symbol on your system."

Example:

Item #1 : 25
Item #2 : 36
Item #3 : 27.5
Item #4 : 28
Item #5 : 32
Item #6 : 33.25
Item #7 : <EOF>


I'm having trouble implementing the CTRL-Z in my program, any ideas?

Code:

/*

My name is Jack Trocinski

*/

#include <stdio.h>
#include <stdlib.h>

int main()
{
	float array[200]; // array of type float with 200 elements
	int i; // used in for loop
	
	for ( i = 0; i < 200; ++i) {
		printf("Please input your data and press enter, use CTRL-Z to when you're done: ");
		scanf("%f", &array[i]);
		
		if (array[i] = EOF) break;
	}
	
	--i;
	
	printf("The number items you have entered is: %d", i);
	
	system("pause");
	return 0;
}

In this line:

Code:

if (array[i] = EOF) break;

You are assigning the EOF to array[i].

This if statement will always be true.

Jim

Your assignment says that to end the loop early, the user will use the EOF value - that is typically -1 in C. Not CTRL+z.

In Windows, it's CRTL+z, but this is not Windows, and the assignment doesn't ask the user to enter CRTL+z.

When you make your file up, you don't need to enter CTRL+z, unless you copy it directly from the console:

Code:

C:\> copy con test.txt <enter>
This is a test<CTRL+z>

  1 file copied
C:\>

The CTRL+z is put into the file, by the program creating the file (Notepad, etc.). In C, it's put in when you close the file, automatically. You never have to add this or -1, to the end of a file in C.

In R/L, if you expected the user to enter -1 as data, you just don't use that as your sentinel value to break out of the enter data loop. Maybe -99 or -9999, or INT_MAX or INT_MIN, etc.

Note that the file won't have a -1 at the end of it. You can check that with a Hex Editor. -1 is EOF for C - a logical construct.

Originally Posted by yacek

Any suggestions, on how to use CTRL-Z to end the input?

Clearly you have not thought about the answers given all that much. tabstop answered this question in the second post.

Check the value returned by scanf(), not the value of array[i].

I've been thinking about this all day Grumpy. Still no idea how to get CTRL-Z to work.

I guess it would return a 0. Nice, I got it to work!

Hmm i thought I had it but it's still not working, doesn't break out of the loop with CTRL-Z. updated code, I added a menu since I'm going to be adding on functions later:

Code:

/*

My name is Jack Trocinski

*/

#include <stdio.h>
#include <stdlib.h>

int main()
{
	float array[200]; // array of type float with 200 elements
	int i; // used in for loop
	int j; // used in menu	
	
	do {
		printf("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\n");
		printf("@                              @\n");
		printf("@ 1. Enter data                @\n");
		printf("@ 2. Display data & statistics @\n");
		printf("@ 3. Exit                      @\n");
		printf("@                              @\n");
		printf("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\n\n");
		
		scanf("%d", &j);

			if (j == 1) {
				for ( i = 0; i < 200; ++i) {
				printf("Please input your data and press enter, use CTRL-Z to when you're done: ");
				scanf("%f", &array[i]);				
				
				if ( array[i] != 1  ) break;
				}
			}
			
	} while (j != 3);

	return 0;
}

Hoorah! That is what tabstop told you to do in the second post of this thread.