Prime Number Generator

C - Prime Number Generator

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

int main()
{	
	int startVar=0,endVar=100;
	
	system("clear");
	printf("Prime Number Generation\n\n");
	printf("Please enter the number to start at: ");
	scanf("%d",&startVar);
	getchar();
	printf("Please enter the number to end at: ");
	scanf("%d",&endVar);
	getchar();
	
	if (startVar>endVar)
	{
		int newEndVar=endVar;
		endVar=startVar;
		startVar=newEndVar;
	}
	
	float x,y;
	int z,iNot,primeNums=0;
	
	int beginTime=time(NULL);	
		
	for (x=startVar;x<=endVar;x++)
	{
		iNot=0;
		if (x>=0)
		{
			for (y=2;y<=(x/2);y++)					
			{
				for (z=(x/y)-1;z<(x/y)+1;z++)				
				{
					if (x/y==z)
					{
						iNot=1;
						y=(x/2)+1;
					}
				}
			}

			if (iNot==0)
			{
				printf("%.0f\n",x);
				primeNums++;
			}

		}
		else
		{
			for (y=-2;y>=x/2;y--)				
			{
				for (z=2;z<(x/y)+1;z++)
				{
					if (x/y==z)
					{
						iNot=1;
						y=(x/2)-1;
					}
				}
			}

			if (iNot==0)
				printf("%.0f\n",x);
		}
	}
	int endTime=time(NULL);
	
	printf("\nTime elapsed for calculation: %d second",endTime-beginTime);
	if (endTime-beginTime==1)
		printf("\n");
	else
		printf("s\n");
	printf("Amount of prime numbers between %d and %d: %d\n",startVar,endVar,primeNums);
	
	getchar();
	return 0;
}