43 lines
814 B
C
43 lines
814 B
C
|
// C version of a Prime Number Finder
|
||
|
|
// Alternate Algorithm: Instead of using sqrt function,
|
||
|
|
// track it with two variables
|
||
|
|
// haplo@mindstab.net
|
||
|
|
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
|
||
|
|
int main(int argc, char **argv)
|
||
|
|
{
|
||
|
|
unsigned int i, x, max=2, isP, sqr=4;
|
||
|
|
unsigned int MAX_NUM;
|
||
|
|
|
||
|
|
if(argc < 2) {
|
||
|
|
printf("primesaltc <MAX NUM>\n");
|
||
|
|
return -1;
|
||
|
|
} else {
|
||
|
|
MAX_NUM = atoi(argv[1]);
|
||
|
|
}
|
||
|
|
if(MAX_NUM < 1)
|
||
|
|
{
|
||
|
|
printf("Invalid MAX_NUM specified\n");
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
for(i=3; i<=MAX_NUM; i+=2)
|
||
|
|
{
|
||
|
|
isP=1;
|
||
|
|
for(x = 3; x<=max; x+=2)
|
||
|
|
{
|
||
|
|
isP = i - (x* (i/x));
|
||
|
|
if(isP == 0) break;
|
||
|
|
|
||
|
|
}
|
||
|
|
if(isP) printf("%d\n", i,max, sqr);
|
||
|
|
|
||
|
|
if(i>=sqr) {
|
||
|
|
max++;
|
||
|
|
sqr = max*max -2;
|
||
|
|
}
|
||
|
|
|
||
|
|
}
|
||
|
|
}
|