为什么这个程序本来要返回美元、25 美分和 10 美分，但数学却没有正确地进行？

Question

我正在尝试编写一个程序，该程序将返回特定整数美分的零钱。例如 92 美分将返回：0 美元、3 个 25 美分、1 毛钱、1 镍币和 2 便士。

这是我到目前为止的代码：

#include <iostream>

using namespace std;

int main() {
    
    // 1. ask user to enter an integer: total cents
    cout << "Hi! Enter an integer representing the total number of cents pls: " << endl;
    
    int user_num{};
    
    // 2. save in std cin
    cin >> user_num;
    
    // 3. check dollars
    int dollars{};
    int add_to_dollars{};
    
    if ( user_num >= 100 ) {             // eg. user_num is 240 
        // calculate amount to add to dollars variable
        add_to_dollars = user_num / 100;              // 240 / 100 = 2.4 keep the 2
        dollars = dollars + add_to_dollars;
        
        // what is the total user_num once we subtract the dollars?  eg. 240 - 200 = 40
        user_num = user_num % 100;              // 240 % 100 = 40
    }
    
    // 4. check quarters
    int quarters{};
    int add_to_quarters{};
    
    if ( user_num >= 25 ) {      // eg. 40
        // how much do we add to quarters variable?
        add_to_quarters = user_numd/25;            //  40 / 25 = 1.6
        quarters = quarters + add_to_quarters;     // add the 1 ^ 
        
        // subtract this to total cents     eg. subtract 25
        user_num = user_num % 25;  
    }
    
    // 5. check dimes
    int dimes{};
    int add_to_dimes{};
    
    if ( user_num >= 10 ) {      
        add_to_dimes = user_num / 10;            
        quarters = quarters + add_to_dimes;     
        user_num = user_num % 10;  
    }

    // 6. check nickels
    int nickels{};
    int add_to_nickels{};
    
    if ( user_num >= 5 ) {      
        add_to_nickels = user_num / 5;            
        quarters = quarters + add_to_nickels;     
        user_num = user_num % 5;  
    }
    
    // 7. check pennies
    int pennies{};
    int add_to_pennies{};
    
    if ( user_num >= 1 ) {      
        add_to_pennies = user_num / 1;            
        quarters = quarters + add_to_pennies;     
        user_num = user_num % 1;  
    }
    
    // 8. return total info of each variable
    cout << "You can provide change for this change as follows: " << endl;
    cout << "dollars: " << dollars << endl;
    cout << "quarters: " << quarters << endl;
    cout << "dimes: " << dimes << endl;
    cout << "nickels: " << nickels << endl;
    cout << "pennies: " << pennies << endl;

    cout << endl;
    return 0;
}

然而，例如，92 美分的答案给了我 7 个 25 美分，而实际上应该是 3 个 25 美分。我是否错误地编写了 C++ 代码，逻辑本质上是错误的吗？提前致谢！

Answer 1

问题是您有一些复制粘贴错误：

quarters = quarters + add_to_dimes; 
// ...
quarters = quarters + add_to_nickels;
// ...
quarters = quarters + add_to_pennies;

这些应该分别使用dimes、nickels和pennies来代替quarters。

为了防止将来出现此类错误，如果您发现自己复制粘贴代码，请考虑将该代码重构为函数。例如，在这种情况下，您可以有一个函数，例如int calculate_partial_change(int total_cents, int coin_denomination)一次处理一种类型的硬币。