c++ - if 语句中的相等比较

Question

对不起这个问题，这是我的第一个 C++ 项目，我有点困惑。我要求用户输入 3 个单独的内容。例如，我从一个数字 80 开始。我要问用户 3 个问题。1）你喜欢蓝色还是黄色？输入 1 表示蓝色，输入 2 表示黄色。如果用户为蓝色输入 1，则将数字 80 乘以 2。如果他们为黄色输入 2，则将 80 乘以 3。

有人可以告诉我这看起来是否在正确的轨道上吗？再次感谢并为初学者的问题感到抱歉。

cout << "Please enter a color blue or yellow. Type 1 for Blue, 2 for Yellow";
cin >> bp1;
// Multiply by 2 if Blue is chosen, 3 if Yellow is chosen.
if (bp1 = 1)
num = num*2;
if (bp1 = 2)
num = num*3;

Answer 1

Welcome to the world of C++! You're definitely on the right track, but there a couple of problems. First, the operator you use in your if statements is the assignment operator, so your statements will always return true. This should actually be the comparison operator (==). Second, I recommend the use of an if-else if statement here, as you may not need to check both times. The following should be sufficient:

if(bp1 == 1)
{
    num = num * 2;
}
else if(bp1 == 2)
{
    num = num * 3;
}

Answer 2

你的意思是写比较运算符==

if (bp1 == 1)
if (bp1 == 2)
//      ^^

if (bp1=1)将始终从operator=

Answer 3

你的 if 语句有问题

它必须是这样的：

if (bp1 == 1)
num = num*2;
if (bp1 == 2)
num = num*3;

Answer 4

更简单：

代替：

if(bp1 == 1)
  num = num * 2;
else if (bp1 == 2)
  num = num * 3;

你可以写这个

  num = num * (bp + 1)

甚至

  num *= (bp + 1)