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Complete the function "int getCount(int begin,int end);" to return the number of prime numbers between the given range "begin" and "end"?

User Mingfei
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1 Answer

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Final answer:

The function getCount calculates the number of prime numbers within a given range by using a helper function isPrime to check each number's primality sequentially, starting from the maximum of 2 or the given begin value, and iterating until the end value.

Step-by-step explanation:

To complete the function int getCount(int begin, int end), you will need to write a program that iterates through each number in the range from begin to end, inclusive, and determines if it is a prime number. A prime number is a whole number greater than 1, whose only two divisors are 1 and itself. Therefore, the starting point of the iteration should be the maximum of 2 and begin, since 2 is the smallest prime number.

The function will then check each number if it is prime by checking if it is divisible by any number from 2 up to its square root. If a number is found to be divisible by any other number besides 1 and itself, it is not prime. If the number is prime, a counter is incremented. After all numbers in the range have been checked, the function returns the total count of prime numbers found.

Below is a pseudocode example of how the function might be structured:

int getCount(int begin, int end) {
int count = 0;
for (int i = max(begin, 2); i <= end; i++) {
if (isPrime(i)) {
count++;
}
}
return count;
}

bool isPrime(int number) {
if (number <= 1) return false;
for (int i = 2; i * i <= number; i++) {
if (number % i == 0) return false;
}
return true;
}

This function uses a helper function isPrime to determine if a single number is prime. This is a straightforward approach, although optimizations like checking only up to the square root, skipping even numbers past 2, or pre-generating a list of primes can be applied for efficiency.

User Mutsu
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