?? writeprimes.java
字號:
import java.io.*;
class WritePrimes {
public static void main(String[] arguments) {
int[] primes = new int[400];
int numPrimes = 0;
// candidate: the number that might be prime
int candidate = 2;
while (numPrimes < 400) {
if (isPrime(candidate)) {
primes[numPrimes] = candidate;
numPrimes++;
}
candidate++;
}
try {
// Write output to disk
FileOutputStream file = new
FileOutputStream("400primes.dat");
BufferedOutputStream buff = new
BufferedOutputStream(file);
DataOutputStream data = new
DataOutputStream(buff);
for (int i = 0; i < 400; i++)
data.writeInt(primes[i]);
data.close();
} catch (IOException e) {
System.out.println("Error -- " + e.toString());
}
}
public static boolean isPrime(int checkNumber) {
double root = Math.sqrt(checkNumber);
for (int i = 2; i <= root; i++) {
if (checkNumber % i == 0)
return false;
}
return true;
}
}
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