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  1. #include <stdio.h>
  2.  
  3. int isprime(int n)
  4. {
  5. 	int	i;
  6.  
  7. 	if (n % 2 == 0) {
  8. 		return n == 2;
  9. 	}
  10. 	for (i = 3; i * i <= n; i += 2) {
  11. 		if (n % i == 0) {
  12. 			return 0;
  13. 		}
  14. 	}
  15. 	return 1;
  16. }
  17.  
  18. int main()
  19. {
  20. 	int	prime[20];
  21. 	int	p;
  22. 	int	i;
  23.  
  24. 	p = 0;
  25. 	for (i = 2; p < 20; i++) {
  26. 		if (isprime(i)) {
  27. 			prime[p++] = i;
  28. 		}
  29. 	}
  30. 	for (p = 0; p < 20; p++) {
  31. 		printf("%2d %d\n", p + 1, prime[p]);
  32. 	}
  33. 	return 0;
  34. }
  35.  
Success #stdin #stdout 0.01s 1720KB
comments (?)
stdin 
Standard input is empty
stdout 
 1 2
 2 3
 3 5
 4 7
 5 11
 6 13
 7 17
 8 19
 9 23
10 29
11 31
12 37
13 41
14 43
15 47
16 53
17 59
18 61
19 67
20 71
https://ideone.com/dEJUB
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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