Created
September 1, 2013 14:46
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//implementation of Sieve of Eratosthenes for prime number generation | |
#include "stdio.h" | |
#include <stdbool.h> | |
#include <stdlib.h> | |
#include <string.h> | |
void prime_no_in_range_simple(int start, int end); | |
void prime_no_in_range_sieve(int start, int end); | |
int main() | |
{ | |
int noItems; | |
int i; | |
printf("Enter no. of items to be entered: \n"); | |
scanf("%d",&noItems); | |
int input[noItems][2]; | |
for (i =0;i!=noItems ;i++ ){ | |
scanf("%d",&input[i][0]); | |
scanf("%d",&input[i][1]); | |
} | |
for (i=0;i!=noItems ;i++ ) { | |
prime_no_in_range_sieve(input[i][0], input[i][1]); | |
printf("\n"); | |
} | |
return 0; | |
} | |
void prime_no_in_range_sieve(int start, int end) | |
{ | |
const int limits = end +1; | |
int number = end; | |
int *db = (int*)malloc(limits*sizeof(int)); | |
int loop; | |
for (loop =2; loop<limits; loop++){ | |
db[loop] = 1; | |
} | |
int multiples; | |
int divisor=2; | |
while(divisor < number) | |
{ | |
for (multiples = divisor*2; multiples <= (number); multiples= (multiples+divisor)) { | |
db[multiples] = 0; | |
} | |
divisor++; | |
} | |
for (loop = 2; loop < (number); loop++) { | |
if((db[loop] == 1) && (loop >= start)) | |
printf("%d\n",loop); | |
} | |
printf("\n"); | |
} | |
void prime_no_in_range_simple(int start, int end) | |
{ | |
int i; | |
for (i=start; i<=end; i++){ | |
int number =i; | |
bool search = true; | |
while(search) | |
{ | |
if (number%2 == 0){ | |
search = false; | |
break; | |
} else { | |
int divisor =3; | |
while(divisor <= (number/2)){ | |
if (number%divisor == 0){ | |
search = false; | |
break; | |
} | |
divisor = divisor+2; | |
} | |
break; | |
} | |
} | |
if (search == true) | |
printf("%d\n", number); | |
} | |
} |
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