對結構向量進行迭代並對迭代器解引用

Question

我在遍歷vector的struct s，然後嘗試對迭代器進行解引用。我想我錯過了一些邏輯並做錯了，或者只是沒有正確的語法。

的代碼如下，並含有大量的調試輸出：

#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 << "\n"; 

    for (unsigned int j = 1; j <= NP; j++) 
    { 
     string giver_name; 
     fin >> giver_name; 
     fout << "Read a name #" << j << ": " << giver_name << "\n"; 

     auto vpit = find_if(accounts.begin(), accounts.end(), [&giver_name](const person& pers) -> bool {return pers.name != giver_name; }); 
     if (vpit == accounts.end()) 
     { 
      fout << "Couldn't find this giver in accounts\n"; 
     } 
     else 
     { 
      person& found = *vpit; // the logic is probably wrong here 
      fout << "\nDebug info: \n\t Giver#" << j << "; \n\t iterator->name ==" << vpit->name << "; \n\t iterator->gave == " << vpit->gave << "; \n\t iterator->received == " << vpit ->received << "\n"; 
      fout << "Found " << found.name << " in accounts; proceeding\n"; 
      //further code 
    } 

什麼可能我是做錯了什麼？

Answer 1

如果你想找到與給定值的向量的元素，那麼你必須使用等於運算符

auto vpit = find_if(accounts.begin(), accounts.end(), 
        [&giver_name] (const person& pers) { return pers.name == giver_name; }); 

至於我，那麼第二個循環

for (unsigned int j = 1; j <= NP; j++) 
{ 
    string giver_name; 
    fin >> giver_name; 
    //... 

看起來可疑地。