C++ Primer 学习笔记——表达式

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//4.1#include<iostream>using std::cout;int main(){    int x = 5 + 10 * 20 / 2;    double y = 5 + 10 * 20 / 2;    cout << x << " " << y;    return 0;}

//4.10#include<iostream>int main(){    int num;    while (std::cin >> num&&num != 42);    return 0;}

//4.13#include<iostream>int main(){    int i ; double b;    b = i = 3.5;//b=3,i=3//  i=b = 3.5;//b=3.5,i=3    std::cout << b << std::endl        << i;    return 0;}

//4.6#include<iostream>#include<vector>using namespace std;int main(){    vector<int> it(0, 10), *iter = &it;    cout << (*iter).empty();    //cout << *iter.empty();    //Error 1   error C2228: left of '.empty' must have class/struct/union  //点运算符的优先级高于解引用，必须加括号    return 0;}

//4.21#include<iostream>#include<vector>using std::vector;using std::cout;int main(){    vector<int> nint{ 12, 34, 2, 54, 55, 345 };    for (auto &i : nint)    {        if (i % 2 != 0 ? (i = i*i) : i = i)            cout << i << " ";    }    return 0;}

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