问题:
见下面的代码和结果
1.加过地址打印,两种方式打印的地址全部完全相同,猜测是for遍历中始终使用一个临时中间遍历
2.不加引用符表征的是复制操作,更改不会同步;加了是别名引用,更改会同步?
3.如果2猜测是对的.那么&(p.name)地址值应该不一样.然后结果还是一样
4.那么该如何解释背后原理?
代码:
#include
#include
#include
#include "fact.h"
using namespace std;
class People {
public:
string name;
People(string n) {
name = n;
}
};
int main(int argc, char** argv) {
cout << "main test start" << endl;
vector ps;
ps.push_back(People("zhangshan"));
ps.push_back(People("lisi"));
ps.push_back(People("wangwu"));
for (auto p : ps){
p.name += "123";
}
for (const auto p : ps){
cout << p.name << endl;
}
cout << "================" << endl;
for (auto &p : ps){
p.name += "123";
}
for (const auto p : ps){
cout << p.name << endl;
}
return 0;
}
结果:
#include
#include
#include
#include "fact.h"
using namespace std;
class People {
public:
string name;
People(string n) {
name = n;
}
};
int main(int argc, char** argv) {
cout << "main test start" << endl;
vector ps;
ps.push_back(People("zhangshan"));
ps.push_back(People("lisi"));
ps.push_back(People("wangwu"));
for (auto p : ps){
p.name += "123";
}
for (const auto p : ps){
cout << p.name << endl;
}
cout << "================" << endl;
for (auto &p : ps){
p.name += "123";
}
for (const auto p : ps){
cout << p.name << endl;
}
return 0;
}