FOR 循环和 IF 语句的问题

Question

尝试显示订购的每个组合的数量和总价。不知道为什么它不会在 A、B 和 C 中存储值。这里是新手程序员，所以要简单。 if 语句的问题已经有一段时间了，所以很明显我做错了整个 if 语句。

#include <iostream>
using namespace std;
int main( )
{
 int group = 0;
 char combo = ' ';
 int A = 0;
 int B = 0;
 int C = 0;
 double total = 0.0;
 cout << "How many customers are in the group? ";
 cin >> group;
 for (int counter = 0; counter < group; counter = counter + 1)
 {
    cout << "Enter combo ordered: ";
    cin >> combo;
    if (combo = A)
    {
        A = A + 1;
        cout << "Enter combo ordered: ";
        cin >> combo;
    }
    else if (combo = B)
    {
        B = B + 1;
        cout << "Enter combo ordered: ";
        cin >> combo;
    }
    else if (combo = C)
    {
        C = C + 1;
        cout << "Enter combo ordered: ";
        cin >> combo;
    }
    total = A*6 + B*6.25 + C*5.75;
 }
 cout << "# of Combo A ordered: " << A << endl;
 cout << "# of Combo B ordered: " << B << endl;
 cout << "# of Combo C ordered: " << C << endl;
 cout << "Total price: $" << total << endl;
 system("pause");
 return 0;
}

Answer 1

for循环应该是for (int counter = 0; counter < group; counter++)

If 语句应该使用== 来表示相等。 = 仅用于分配。

您的if 语句需要引用您要比较的字符：if (combo == 'A') {。您也可能需要将组合作为字符数组访问，如下所示：if (combo[0] == 'A') {

Answer 2

我认为您可能只需要调整一些东西；当您使用int 计算double 时，一些编译器不喜欢它，并且没有理由不在这里使用double，因为程序很小。还有一些语法错误（即使用= 而不是==）。您是否尝试过以孤立的方式显示您的输出？比如：

main(){
double A = 1;
double B = 2;
double C = 3;
double total = A*6 + B*6.25 + C*5.75;

 cout << "# of Combo A ordered: " << A << endl;
 cout << "# of Combo B ordered: " << B << endl;
 cout << "# of Combo C ordered: " << C << endl;
 cout << "Total price: $" << total << endl;
 system("pause");
 return 0;
}

您更正的代码：

#include <iostream>
using namespace std;
int main( )
{
 int group = 0;
 char combo = ' ';
 double A = 0;
 double B = 0;
 double C = 0;
 double total = 0.0;
 cout << "How many customers are in the group? ";
 cin >> group;
 for (int counter = 0; counter < group; counter++)
 {
    cout << "Enter combo ordered: ";
    cin >> combo;
    if (combo == 'A')
    {
        A++;
    }
    else if (combo == 'B')
    {
        B++;
    }
    else if (combo == 'C')
    {
        C++;
    } 
    cout << "Enter combo ordered: ";
    cin >> combo;       
 }

 total = A*6 + B*6.25 + C*5.75;

 cout << "# of Combo A ordered: " << A << endl;
 cout << "# of Combo B ordered: " << B << endl;
 cout << "# of Combo C ordered: " << C << endl;
 cout << "Total price: $" << total << endl;
 system("pause");
 return 0;
}

我还会显示group 的值，以确保if 循环甚至至少运行一次。这里有几个故障点，我会单独测试。

---

编辑：

也许可以测试一下：

#include <iostream>
using namespace std;
int main( )
{
 int group = 0;
 cout << "How many customers are in the group? ";
 cin >> group;
 for (int counter = 0; counter < group; counter++)
 {
    cout << "Test success";
 }

看看你是否进入了for循环。