素数2

#include <stdlib.h> // malloc
#include <iostream>

main( int argc, char *argv[] ) {
	long int i, j, N = atol(argv[1]);
	int *a = malloc(N*sizeof(int));

	if ( a == NULL ) {
		printf("Insufficient memory.\n");
		return 1;
	}
	
	for ( i = 2; i < N; i++ ) {
		a[i] = 1;
	}	

	for ( i = 2; i < N; i++  ) {
		if ( a[i] ) {
			for( j = i; i*j < N; j++ ) {
				a[i*j] = 0;
			}
		}
	}

	for ( i = 2; i < N; i++ ) {
		if( a[i] ) {
			printf( "%4d", i );
		}
	}
	
	printf("\n");
	system("pause");
}