C++之判断一个数是否为素数

#include <iostream>
#include "math.h"

using namespace std;

bool isPrimeNumber(int number) { //判断是否为素数
    float sqrtOfNum = sqrt(number);
    for (int j = 2; j <= sqrtOfNum; j++) //从2到number的算术平方根迭代
        if (number / j * j == number) //判断j是否为number的因数
            return false;
    return true;
}

void printNum(int number) { //打印出 <= number的所有质数
    int j = 0;
    for (int i = 2; i <= number; i++)
        if (isPrimeNumber(i) == true) {
            cout << ("%-5d", i) << " ";
            j++;
            if (j % 10 == 0) //每隔十个数字换行
                cout << endl;
        }
}

int main() {
    long start = time(NULL);
    cout << (bool) isPrimeNumber(29) << endl;
    printNum(1000);
    long end = time(NULL);
    cout << endl << "Time spent: " << (end - start + 1) << endl;
}#include <iostream>
#include "math.h"

using na