Thread: Input Checks

Hi all,

I need to write a program which you input up to 10 numbers, and it sorts them into ascending, descending and random ordering.

It also needs to alert the user when a float or a char is entered, as it can only take integers.

The rest is pretty much sorted, but how would I go about altering the program such that the user is alerted and re-prompted to enter the value? I'm guessing the main function will have to be re-written.

The program:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
/*Prototype declarations */

void sort(int inputValues[], int promptCount);

int main()
{
	int inputValues[10], promptCount, count1, count2;
	inputValues[10] = 0;
	printf("Please Enter Your Values (as Integers - up to 10 Values Maximum). If you require less than 10 values, please enter any negative Integer.\n");
	
	for(promptCount = 0; promptCount < 10; promptCount++)
		{	
			printf("\nEnter the #%d value:", (promptCount+1));
			
			scanf("%d", &inputValues[promptCount]);
		}
	
	sort(inputValues, promptCount);
	
	printf("\nArranged in Ascending Order:");
   for (count1 = 0; count1 < 10; count1++)
			printf(" %d,", inputValues[count1]);
	
	printf("\nArranged in Descending Order:");
   for (count2 = 9; count2 > -1; count2--)
			printf(" %d,", inputValues[count2]);
}

void sort(int inputValues[], int promptCount)
/* Bubble Sort. */
{
	int i, j, temp;
	for(i = 0; i < (promptCount); i++)
		{
			for (j = 0; j < (promptCount - i - 1); j++)
				{
					if( inputValues[j] > inputValues[j + 1] )
						{
							temp = inputValues[j];
							inputValues[j] = inputValues[j + 1];
							inputValues[j + 1] = temp;
						}
				}
		}
}

> scanf("%d", &inputValues[promptCount]);
http://faq.cprogramming.com/cgi-bin/...&id=1043284385
http://faq.cprogramming.com/cgi-bin/...&id=1043284385

Basically,
- read a line using fgets
- validate the line in some way
- convert the line in some way

There are many possible choices for what to do once you've read the line from the user.

> I presume the first if statement is there to see if the input is blank (just hit enter),
No, fgets() returns NULL at EOF, not on an empty line
Use another inner if() statement to check for a string length of zero, after you've done removing the \n.

> Any ideas?
Maybe a loop which swaps pairs of elements of the array you've input?