c++ - 如何计算 “numbers in for”的数量

Question

大家，我建立了一个程序，可以从给定的数字中知道偶数和奇数。

偶数和奇数工作得很好，我想知道从开始到结束的数字总数，但是对于两者，输出总说11。
我该如何解决？并且有任何计数字母/数字的功能，因为它将非常有帮助。
我确实搜索过，但是找不到任何谢谢

#include<stdio.h>
#include <iostream>
using namespace std;


int main(){

    int number;
    int firstNum,secondNum;
    int countOdd,countEven;

    cout << "Enter the first number: ";
    cin >> firstNum;

   cout << "Enter the second number: ";
    cin >> secondNum;

if (firstNum>secondNum )
    cout << "Sorry the first number must be less than second number";

else

    cout << "Odd numbers in given range are: ";
    for(number = firstNum;number <= secondNum; number++)

         if(number % 2 !=0)
             cout << number<< " ";
     countOdd = number;
     cout << "\nTotal count of odd number is :" << countOdd << endl;

    printf("\nEven numbers in given range are: ");
    for(number = firstNum;number <= secondNum; number++)

         if(number % 2 ==0)
             cout << number << " ";
 countEven = number;
     cout << "\nTotal count of even number is :" << countEven << endl;

    return 0;
}

Answer 1

计算奇数和偶数的代码:

using namespace std; 

// Return the number of odd numbers  
// in the range [L, R]  
int countOdd(int L, int R){  

    int N = (R - L) / 2; 

    // if either R or L is odd  
    if (R % 2 != 0 || L % 2 != 0)  
        N += 1; 

    return N; 
} 

// Driver code 
int main() 
{  
    int L = 3, R = 7; 
    int odds = countOdd(L, R);  
    int evens = (R - L + 1) - odds;  

    cout << "Count of odd numbers is " << odds << endl;  
    cout << "Count of even numbers is " << evens << endl; 
    return 0; 
}