问题描述
我一直在研究这个代码，一切都很好，直到编译器给我一个错误 C：\ Users\dcst\Desktop\file\main.cpp | 108 |错误：否匹配'collection<<'in'collection<< ctr'| 如果我不能正确使用这种方法，我就无法继续处理其他事情。
I've been working on this code, everything's been fine until the compiler gave me an error C:\Users\dcst\Desktop\file\main.cpp|108|error: no match for 'operator<<' in 'collection << ctr'| and I can't continue working on the other things if I can't do this method right.
#include <iostream>
#include <fstream>
#include <string>
#include <stdlib.h>
using namespace std;
struct students{
string studentID;
string surname;
string firstname;
string birthdate;
string sex;
};
int main()
{
fstream collection;
string filename;
short choice;
do{
int ctr=1;
system("cls");
if(collection.is_open()){
cout<<"Active File: ["<<filename<<"]"<<endl;
}else{
cout<<"Active File|: [None opened]"<<endl;
}
cout<<"[1] Create new file"<<endl;
cout<<"[2] Open existing file"<<endl;
cout<<"[3] Manage data"<<endl;
cout<<"[4] Exit"<<endl;
cout<<"Enter operation index: ";
cin>>choice;
switch(choice){
default:
cout<<"Invalid input."<<endl;
system("pause");
choice=4;
break;
case 1:
cout<<"Enter file name: ";
cin>>filename;
collection.open(filename, std::fstream::in | std::fstream::out | std::fstream::app);
collection<<"------------------------------------------------------------------------------"<<endl;
collection<<"Rec \t Student ID \t Surname \t Firstname \t Birthdate \t Sex \t"<<endl;
collection<<"------------------------------------------------------------------------------"<<endl;
collection.close();
collection.open(filename, std::fstream::in | std::fstream::out | std::fstream::app);
break;
case 2:
cout<<"Enter file name: ";
cin>>filename;
collection.open(filename, std::fstream::in | std::fstream::out | std::fstream::app);
break;
case 3:
string lines;
char menu;
students student[10];
do{
if(collection.is_open()){
cout<<"Active File: ["<<filename<<"]";
system("cls");
while(getline(collection,lines)){
cout<<lines<<endl;
}
}
collection.close();
collection.open(filename, std::fstream::in | std::fstream::out | std::fstream::app);
cout<<"[A]dd [E]dit [D]elete [S]ort [F]ilter Sa[V]e e[X]it"<<endl;
cout<<"Enter operation: ";
cin>>menu;
if(menu=='A'){
string lines2;
int one;
int two;
collection.open(filename,ios::app);
system("cls");
ifstream collection(filename, std::fstream::in | std::fstream::out | std::fstream::app);
if(collection.is_open()){
while(getline(collection,lines)){
cout<<lines<<endl;
}
}
collection.close();
cout<<endl<<"Adding data to "<<filename<<endl;
cout<<"Student ID: ";
cin>>student[ctr].studentID;
cout<<"Surname: ";
cin>>student[ctr].surname;
cout<<"Firstname: ";
cin>>student[ctr].firstname;
cout<<"Birthdate: ";
cin>>student[ctr].birthdate;
cout<<"Sex: ";
cin>>student[ctr].sex;
collection.open(filename, std::fstream::in | std::fstream::out | std::fstream::app);
collection<<ctr<<"\t"<<student[ctr].studentID<<"\t"<<student[ctr].surname<<"\t"<<student[ctr].firstname<<"\t"<<student[ctr].birthdate<<"\t"<<student[ctr].sex<<endl;
collection.close();
system("pause");
ctr++;
collection.open(filename, std::fstream::in | std::fstream::out | std::fstream::app);
}else if(menu=='E'){
}else if(menu=='D'){
}else if(menu=='F'){
}else if(menu=='V'){
cout<<"Saving file..."<<endl;
collection.close();
cout<<"File saved."<<endl;
system("pause");
}else{
system("pause");
};
}while(menu!='X');
break;
}
}while(choice!=4);
}
我的尝试：
我试过这样做
collection.open（filename，std :: fstream :: in | std :: fstream :: out | std :: fstream :: app）;
collection<< ctr<<\t<< student [ctr] .studentID<< \\t <<学生[CTR] .surname<< \t <<学生[CTR] .firstname<< \t<<学生[CTR] .birthdate< <\t<< student [ctr] .sex<< endl;
collection.close（）;
但我一直收到错误
What I have tried:
I've tried to do this
collection.open(filename, std::fstream::in | std::fstream::out | std::fstream::app);
collection<<ctr<<"\t"<<student[ctr].studentID<<"\t"<<student[ctr].surname<<"\t"<<student[ctr].firstname<<"\t"<<student[ctr].birthdate<<"\t"<<student[ctr].sex<<endl;
collection.close();
but I keep getting that error
推荐答案
ifstream collection(filename, std::fstream::in | std::fstream::out | std::fstream::app);
// ...
collection.close();
// ...
collection.open(filename, std::fstream::in | std::fstream::out | std::fstream::app);
// Output operator << not present with istream based classes
collection<<ctr; // ...
要使用一个流执行输入和输出，请使用 fstream 类。但在您的情况下，最好使用新的输出流对象进行写入。
To perform input and output with one stream use the fstream class. But in your case it might be better to use a new output stream object for writing.
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