在结构中初始化结构向量

Question

Reading a structured file of temperature readings Example - From pages 369–370 of Programming: Principles and Practices using C++:

 struct Day { vector<double> hour {vector<double>(24,not_a_reading)}; }; 

That is, a Day has 24 hours, each initialized to not_a_reading.

 struct Month { // a month of temperature readings int month {not_a_month}; // [0:11] January is 0 vector<Day> day {32}; // [1:31] one vector of readings per day }; 

We “waste” day[0] to keep the code simple.

 struct Year { // a year of temperature readings, organized by month int year; // positive == AD vector<Month> month {12}; // [0:11] January is 0 }; 

Each class is basically a simple vector of “parts,” and Month and Year have an identifying member month and year, respectively.

Shouldn't brackets be used instead of curly braces, if the goal is to create a vector of type day/month that has 32/12 members?

Answer 1

The curly braces lets the compiler know that you want to initialize using an initializer list.

Brackets are used to access vector elements.