关于std::vector指针的下标“[]”的使用

#include <cstdlib>
#include <iostream>
#include <set>
#include <vector>

using namespace std;

struct test_t {
       uint32_t a;
       uint32_t b;
};

int main(int argc, char *argv[])
{
    test_t t;
    memset(&t, 0x00, sizeof(test_t));
    t.a = 4;

    std::vector<test_t>* vec = new std::vector<test_t>;
    vec->push_back(t);
   
    cout<<vec[0].a<<endl;
   
    vec->clear();
    delete vec;
    system("PAUSE");
    return EXIT_SUCCESS;
}

编译后：

28 E:/software/DEV-CPP/project/main.cpp 'class std::vector<test_t, std::allocator<test_t> >' has no member named 'a'

 

修改为：

    cout<<(*vec)[0].a<<endl;

编译后运行正常，结果为：4