43 lines
788 B
C++
43 lines
788 B
C++
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/* Eratosthenes Sieve Prime Number Program in C, Byte January 1983.
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* The code has been corrected to produce primes correctly.
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*/
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#include <stdio.h>
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#define TRUE 1
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#define FALSE 0
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#define NITER 150
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#define SIZE 8190
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char flags[SIZE+1]={0};
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main ()
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{
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register int i,k;
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int iter, count;
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printf ("%d iterations: ", NITER);
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for( iter = 1; iter <= NITER; iter++ ) /* Do sieve 150 times */
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{
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count = 0;
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for( i = 0; i <= SIZE; i++) /* set all flags true */
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flags[i] = TRUE;
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for( i = 2; i <= SIZE; i++ )
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{
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if ( flags[i] ) /* found a prime */
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{
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for ( k = i + i; k <= SIZE; k += i )
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flags[k] = FALSE; /* Cancel its multiples */
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count++;
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}
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}
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}
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printf ("%d primes\n", count);
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exit(0);
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}
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