Written in C language An integer is said to be prime if it\'s divisible by only
ID: 3758727 • Letter: W
Question
Written in C language
An integer is said to be prime if it's divisible by only 1 and itself. For example, 2, 3, 5, and 7 are prime, but 4, 6 8, and 9 are not.
a)write a function that determines whether a number is prime.
b)Use this function in a program that determines and prints all prime numbers between 1 and 10,000. How many of these 10,000 numbers do you really have to test before being sure that you have found all the primes?
c)Initially you might think that n/2 is the upper limitfor which you must test to see whether a number is prime, but you need go only as high as the square root of n. Re-write the program, and run it both ways. Estimate the program improvement.
Explanation / Answer
#include<stdio.h>
bool isPrime(int n){
int i;
for (i=2; i< sqrt(n); i++)
{
if (n % i == 0)
{
return false;
}
}
return true;
}
int main(){
int n = 2;
int i = 0;
while( n+i <= 10000){
if(isPrime(n+i))
cout<<n+i<<" ";
if(i % 10 == 0)
cout<<endl;
i++;
}
}
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