63 lines
1.8 KiB
C
63 lines
1.8 KiB
C
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#include <stdio.h>
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#include <malloc.h>
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#define MAX_NUM 50
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// array will be initialized to 0 being global
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int primes[MAX_NUM];
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void gen_sieve_primes(void)
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{
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int p;
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// mark all multiples of prime selected above as non primes
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int c = 2;
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int mul = p * c;
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for (p = 2; p < MAX_NUM; p++) // for all elements in array
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{
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if (primes[p] == 0) // it is not multiple of any other prime
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primes[p] = 1; // mark it as prime
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for (; mul < MAX_NUM;)
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{
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primes[mul] = -1;
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c++;
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mul = p * c;
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}
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}
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}
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void print_all_primes()
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{
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int c = 0, i;
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for (i = 0; i < MAX_NUM; i++)
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{
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if (primes[i] == 1)
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{
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c++;
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if (c < 4)
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{
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switch (c)
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{
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case 1:
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printf("%d st prime is: %d\n", c, i);
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break;
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case 2:
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printf("%d nd prime is: %d\n", c, i);
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break;
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case 3:
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printf("%d rd prime is: %d\n", c, i);
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break;
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default:
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break;
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}
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}
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else
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printf("%d th prime is: %d\n", c, i);
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}
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}
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}
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int main()
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{
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gen_sieve_primes();
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print_all_primes();
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return 0;
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}
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