Step 1 Fill an array num[100] with numbers from 1 to 100
Step 2 Starting with the second entry in the array, set all its multiples to zero.
Step 3 Proceed to the next non-zero element and set all its multiples to zero.
Step 4 Repeat step 3 till you have set up the multiples of all the non-zero elements to zero
Step 5 At the conclusion of step 4, all the non-zero entries left in the array would be prime numbers, so print out these numbers.
#include<stdio.h>
#include<conio.h>
int main()
{
int a[100], i, j, curr;
for (i = 0; i < 100; i++)
a[i] = i + 1;
for (i = 1; i < 100; i++)
{
if (a[i] == 0)
continue;
curr = a[i];
for (j = i + 1; j < 100; j++)
{
if (a[j]%curr == 0)
a[j] = 0;
}
}
printf("\n");
for (i = 0; i < 100; i++)
{
if (a[i] == 0)
continue;
printf("%d\t", a[i]);
}
printf("\n");
_getch();
return 0;
}