向量中的结构成员在C ++中是否用零初始化？

在这种情况下，由于的属性，答案为是std::vector::resize()：

If the current size is less than count, additional elements are appended and initialized with copies of value.      (until C++11)

If the current size is less than count,  (since C++11)
    1) additional value-initialized elements are appended
    2) additional copies of value are appended

对于正常情况，答案将是“否”，例如myStruct s，这将使它们（s.i, s.bool, s.myobj）的值不确定。

如果仍然希望按预期方式对其进行初始化，请为该结构创建一个构造函数：

struct myStruct {
    int i;
    bool b;
    MyClass *myobj;

    myStruct():i(0),b(false),myobj(NULL) { }  // <- set them here by default
};