c++ - C++如果条件运算符被左关联怎么办

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我发现这个问题我真的不知道答案。假设我们有以下代码：

int grade = 100;
string finalgrade = (grade > 90) ? "High Pass"
                                 : (grade > 75) ? "Pass"
                                                : (grade >= 60) ? "low pass" : "fail";

如果将条件运算符置于关联状态，将如何评估？

最佳答案

如果?:是左关联的，则意味着：

a ? b : c ? d : e

等同于：

(a ? b : c) ? d : e

代替：

a ? b : (c ? d : e)

将其应用于您的示例，您将获得：

string finalgrade =   (  (  (grade > 90)
                          ? "High Pass"
                          : (grade > 75))
                       ? "Pass"
                       : (grade >= 60))
                    ? "low pass"
                    : "fail";

假设编译器没有抱怨类型不匹配的情况，对于grade = 100，这将导致：

string finalgrade =   (  (  true
                          ? "High Pass"
                          : (grade > 75))
                       ? "Pass"
                       : (grade >= 60))
                    ? "low pass"
                    : "fail";

string finalgrade =   (  "High Pass"
                       ? "Pass"
                       : (grade >= 60))
                    ? "low pass"
                    : "fail";

string finalgrade =   "Pass"
                    ? "low pass"
                    : "fail";

string finalgrade = "low pass";

关于c++ - C++如果条件运算符被左关联怎么办，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/17743354/