为什么使用=来初始化C ++中的原始类型？ [英] Why use = to initialise a primitive type in C++?

问题描述

在我工作的地方，人们通常认为对象最好使用C ++风格构造（带括号）初始化，而原始类型应该使用=运算符初始化：

Where I work, people mostly think that objects are best initialised using C++-style construction (with parentheses), whereas primitive types should be initialised with the = operator:

std::string strFoo( "Foo" );
int nBar = 5;

没人能解释为什么他们喜欢这种方式。我可以看到， std :: string =Foo; 将是低效的，因为它将涉及一个额外的副本，但是错误的只是废除 = 运算符，并使用括号到处？

Nobody seems to be able to explain why they prefer things this way, though. I can see that std::string = "Foo"; would be inefficient because it would involve an extra copy, but what's wrong with just banishing the = operator altogether and using parentheses everywhere?

这是一个常见的约定吗？

Is it a common convention? What's the thinking behind it?

推荐答案

除非你已经证明它对性能很重要，否则我不担心在您的示例中使用赋值运算符（ std :: string foo =Foo; ）进行额外复制。如果这个副本甚至存在，一旦你看到优化的代码，我相信，实际上会调用相应的参数化构造函数。

Unless you've proven that it matters with respect to performance, I wouldn't worry about an extra copy using the assignment operator in your example (std::string foo = "Foo";). I'd be pretty surprised if that copy even exists once you look at the optimized code, I believe that will actually call the appropriate parameterized constructor.

在回答你的问题，是的，我会说这是一个相当普遍的约定。通常，人们使用赋值来初始化内置类型，并没有一个令人信服的理由来改变传统。可读性和习惯是这个约定的完美有效的原因，因为它对最终代码的影响很小。

In answer to your question, yes, I'd say that it's a pretty common convention. Classically, people have used assignment to initialize built-in types, and there isn't a compelling reason to change the tradition. Readability and habit are perfectly valid reasons for this convention given how little impact it has on the ultimate code.

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