Thread: How-to not to Storing Array that is used to terminate

I was trying to get input from keyboard and place it in array. If the user input is -1, the program should end itself. This thing really work. The requirement i wanted is,

• -1 is used to terminate<<----work

• -1 will not be stored in array<<----not really

Code:

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

int main(){
	int num[]={};
	int count=0;
	double total=0;
	int count2=1;
	
	printf("Input Value into Array\n");
	
	while(num[count]!=-1){
		count++;
		printf("value:");
		scanf("%d", &num[count]);
		total = total + num[count];
		count2++;
	}
	printf("Total count: %d\n",count);
	
	printf("Value inserted: ");
	for(count=1;count<count2;count++){
	printf("%d  ",num[count]);	
	}
}

Ok... referring to message #1...

Line 5... you have to give the array a size, C does not know how to expand an array as you stuff new things into it. You are writing data to memory you don't own and if it appears to work, that is just pure dumb luck. eg. int num[100];

line 12... the while loop should exit on the maximum size set in Line 5... eg while (count < 100)... to prevent array overflows.

line 13 to line 17 replace with...

Code:

printf("Enter value :");
scanf("%d",&num[count]);
if (num[count] == -1)
  break;
count ++;

Line22 ... should use your count2 variable ...

Code:

for (count2 = 0;count2 < count; count2++)
   printf("%d  ",num[count2]);

Also, you should be aware that C arrays start at 0, not 1... thus an array[10] has valid index values from 0 to 9 ... not 1 to 10...

Thanks for your advice.