【Accelerated C++】读书笔记(一)

#include<iostream>#include<string>#include<vector>#include<algorithm> //sort#include <iomanip> //setprecisionusing namespace std;int main(){std::cout << "Please enter your name:" ;std::string name;std::cin >> name; //写入namestd::cout << "Hello!" << name << std::endl;int count =0;double sum = 0;double x;while(std:cin>>x){++count;sum +=x;}vector<double> homework;while(std::in>>x){homework.push_back(x);}//把vec_sz作为vector<double>::size_type的别名//vector<T>::size_type 一种类型typedef vector<double>::size_type vec_sz;vec_sz size = homework.size();if(size ==0){cout << endl <<"you must enter your greades";return 1; //非0代表程序结束 }sort(homework.begin(),homework.end()); //#include<algorithm>vector<double>& hw = homework; // hw 是homework的一个替代名const vector<double>& chw = homework; // chw是homework的另一个替代名,确保了不会对chw改变它值的动作vector<double>& hw2 = chw; //错了：请求对chw的写访问//输出结果streamsize prec = cout.precision();cout << "your final grade is " << setprecision(3); //3位有效位数return 0;}

 

//1.include "" <>区别
<>从标准库开始找，“”从我们编译的文件开始找
//2.for(int i =0;i!=rows;++i) for(int i=1;i <= rows;++i)区别
原因一：从0开始使循环更易于表达，可直接看出我们已经输出了i行
原因二：确保循环条件等于rows而不是rows+1