c++ 20 format 基本使用方法

#include <iostream>
#include <format>
#include <cmath>

int main()
{
    double pricipal{ 1000.00 };
    double rate{ 0.05 };

    std::cout << std::format("Initial Pricipal: {:>7.2f}\n", pricipal);
    std::cout << std::format("Initial Rate: {:>7.2f}\n", rate);

    std::cout << std::format("\n{}{:>20}\n", "Year", "Amount on deposit");

    for (int year{1}; year <= 10; ++year)
    {
        double amount = pricipal * pow(1.0 + rate, year);
        std::cout << std::format("{:>4d}{:>20.2f}\n", year, amount);
    }

}

{:>7.2f} 的意思是
‘：’代表开始声明格式
‘>’ 代表右对齐
7 代表占7个字符位置大小，用空格填充
.2f代表保留两位小数