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没有else的多个if语句

if-statement c++

-1

b w · 技术社区 · 6 年前

我不允许使用 else ,但我可以使用 if

这是我目前掌握的代码:

#include <iostream>
#include <iomanip>
#include <string>
using namespace std;

int operand1;
int operand2;
float output;
char action;

int main()
{
   cout << fixed << showpoint << setprecision(2);

   cout << "Enter the initial balance [1-1000]: " << endl;
   cin >> operand1;

   cout << "Enter an action (D, W, I or C):" << endl;
   cin >> action;

   cout << "Enter the second operand:" << endl;
   cin >> operand2;

   if ((action != 'D' && action != 'W' && action != 'I' && action != 'C') || (operand1 > 1000 || operand1 < 1) || 
       (action == 'I' && operand2 > 15 || operand2 < 1) || (action == 'C' && operand2 != 20 && operand2 != 10 && operand2 != 5) ||
       (operand2 > 1000 || operand2 < 1))
   {
       cout << "Input out of range" << endl;
       return 0;
   }

   if (action == 'D')
   {
      output = (operand1 + operand2);
      cout << "The new account balance is " << output << endl;
   }

   if (action == 'W')
   {
      output = (operand1 - operand2);
      if (output<0)
      {
          cout << "Input out of range" << endl;
          return 0;
      }
       cout << "The new account balance is " << output << endl;
   }

   if (action == 'I')
   {

       output = ((float)operand1 + (((float)operand2 / 100) * (float)operand1));
       cout << "The new account balance is " << output << endl;
   }

   if (action == 'C')
   {
       output = operand1 % operand2;
       cout << operand1 / operand2 << " bills dispensed plus " << output << endl;
   }

    cin.get();
    cin.get();
    return 0;
}

Enter the initial balance [1-1000]: 1030

Enter an action (D, W, I or C): D

Enter the second operand: 40

Input out of range

Enter the initial balance [1-1000]:

1030

Input out of range

Enter an action (D, W, I or C):

D

Enter the second operand:

40

The new account balance is 1070.00

声明。

3 回复 | 直到 6 年前

dszakal 6 年前

使用开关(操作):

https://en.cppreference.com/w/cpp/language/switch

在这种情况下,它可以有一个默认值。

还有很多习俗禁止其他的,但不是禁止elseif-你确定elseif在你的情况下是禁止的吗?

但即使允许elseif,switch也更适合阅读,是一个更优雅的解决方案。

S.R. 6 年前

您可以通过将所有命令作为不同的案例来使用switch。这是其他人已经说过的话。

Joop Eggen 6 年前

&& 优先级高于 ||

if (
    (action != 'D' && action != 'W' && action != 'I' && action != 'C') ||
    (operand1 > 1000 || operand1 < 1) ||
//  (action == 'I' && operand2 > 15 || operand2 < 1) ||
    (action == 'I' && (operand2 > 15 || operand2 < 1)) ||
    (action == 'C' && operand2 != 20 && operand2 != 10 && operand2 != 5) ||
    (operand2 > 1000 || operand2 < 1))
{
    cout << "Input out of range" << endl;
    return 0;
}

为了在代码的功能上有更多的可追溯性,值得付出努力:

if (action != 'D' && action != 'W' && action != 'I' && action != 'C')
{
    cout << "Input out of range; action " << action << endl;
    return 0;
}
if (operand1 > 1000 || operand1 < 1)
{
    cout << "Input out of range; 1st operand: " << operand1 << endl;
    return 0;
}
...