summary: sizeof

最新推荐文章于 2024-05-11 16:20:55 发布

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最新推荐文章于 2024-05-11 16:20:55 发布

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分类专栏： C++ 文章标签： sizeof

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本文详细解释了 C++ 中 sizeof 运算符的功能和用法，包括其如何应用于基本类型、引用、指针、数组及字符串等不同场景，并介绍了 C++11 新标准中对类成员使用 sizeof 的方法。

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The result of applying sizeof depends in part on the type involved:

*) sizeof char or an expression of type char is guaranteed to be 1.

*) sizeof a reference type returns the size of an object of the referenced type.

*) sizeof a pointer returns the size needed hold a pointer.

*) sizeof a dereferenced pointer returns the size of an object of the type to which the pointer points; the pointer need not be valid.

*) sizeof an array is the size of the entire array. It is equivalent to taking the sizeof the lement type times the number of elements in the array. Note that sizeof does not convert the array to a pointer.

*) sizeof a string or a vector returns only the size of the fixed part of these types; it does not return the size used by the object's elements.

C++11:

Under the new standard, we can use the scope operator to ask for the size of a member of a class type. Ordinarily we can only access the members of a class through an object of that type. We don't need to supply an object, because sizeof does not need to fetch the member to know its size.