無法從字符串成員的結構向量中讀取名稱

Question

我正在將某個數據從文件讀取到vector<struct>。該代碼是這樣的：

#include <fstream> 
#include <map> 
#include <string> 
#include <vector> 
#include <algorithm> 

using namespace std; 

int main() 
{ 
    ifstream fin("gift1.in", ios::in); 
    ofstream fout("gift1.out", ios::out); 

    unsigned short NP; 

    struct person 
    { 
     string name; 
     unsigned int gave; 
     unsigned int received; 
    }; 

    vector<person> accounts; 

    string tmp_name; 

    fin >> NP; 
    accounts.resize(NP); 
    for (auto i : accounts) 
    { 
     fin >> tmp_name; 
     fout << "Just read this name: " << tmp_name << "\n"; 
     i.name = tmp_name; 
     i.gave = 0; 
     i.received = 0; 

     fout << "We have just created this person: " << i.name << ";" << i.gave << ";" << i.received << "\n"; 
//(1) 
     // OK, this part works 
    } 

    fout << "Freshly created ledger:\n"; 
    for (auto l : accounts) 
     fout << "Person: " << l.name << "; Gave: " << l.gave << ";Received " << l.received << "\n"; 
//irrelevant stuff further 
} 

的proble是名在(1)循環打印出來，但他們不是在遠程for循環。 這是爲什麼呢？

示例輸出是這樣的：

Just_read_this_name：_mitnik We_have_just_created_this_person：_mitnik; 0; 0 Just_read_this_name：_Poulsen We_have_just_created_this_person：_Poulsen; 0; 0 Just_read_this_name：_Tanner We_have_just_created_this_person：_Tanner; 0; 0 Just_read_this_name：_Stallman We_have_just_created_this_person：_Stallman; 0; 0 Just_read_this_name：_Ritchie We_have_just_created_this_person：_Ritch即; 0; 0 Just_read_this_name：_Baran We_have_just_created_this_person：_Baran; 0; 0 Just_read_this_name：_Spafford We_have_just_created_this_person：_Spafford; 0; 0 Just_read_this_name：_Farmer We_have_just_created_this_person：_Farmer; 0; 0 Just_read_this_name：_Venema We_have_just_created_this_person：_Venema; 0; 0 Just_read_this_name：_Linus We_have_just_created_this_person：_Linus; 0; 0 Freshly_created_ledger： 人：_; _都給：_0; Received_0 人：_; _都給：_0; Received_0 人：_; _都給：_0; Received_0 人： _; _都給：_0; Received_0 人：_; _都給：_0; Received_0 人：_; _都給：_0; Received_0 人：_; _都給：_0; Received_0 人：_; _都給：_0; Received_0 人： _; _都給：_0; Received_0 人：_; _都給：_0; Received_0

Answer 1

for (auto i : accounts) 

每個i，你得到的是一個元素的accounts副本。當你做i.name = tmp_name時，你只是修改這個副本。您需要參考，以便您可以修改元素本身：

for (auto& i : accounts)