[英]How can I write C++ fstream to file?
I have a problem with this code. 我对此代码有疑问。 Could you please help me to find out why it does not save new total donation values (total) to the file (donation_total.txt)?
您能否帮助我找出为什么它不将新的捐赠总额(总计)保存到文件(donation_total.txt)中? It should be noted that the default value saved in the file is zero, but it keeps it for each iteration.
应该注意的是,文件中保存的默认值为零,但每次迭代都会保留默认值。 I need the new value is saved at the last line each time.
我需要每次将新值保存在最后一行。
Thanks 谢谢
#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
using namespace std;
int main()
{
fstream records;
records.open("donation_total.txt", ios_base::in | ios_base::out | ios_base::app);
if (records.is_open())
{
cout << "The record file is open!" << endl;
string line;
while (!records.eof())
{
getline(records, line);
}
int total = stoi(line);
cout << "Total donation is: "<<total << endl;
cout << "Is there any new record?" << endl;
string str,newname;
stringstream field;
string name;
int donation;
getline(cin , str);
while (str=="Yes" | str=="yes")
{
cout << "Enter name and donation value: ";
getline(cin, newname);
field.str(newname);
field >> name >> donation;
total += donation;
field.clear();
cout << name << " donates " << donation << "$" << endl;
cout << "Total donation is: " << total << endl;
records << endl << total;
cout << "Is there any new record?" << endl;
getline(cin, str);
}
}
else
{
cerr << "Could not find the file!" << endl;
}
records.close();
return 0;
}
Your program has many logical incorrectness. 您的程序有很多逻辑上的错误。 When a name is entered with no donation amount, it takes the previously donated value.
输入没有捐赠金额的名称时,它将采用先前捐赠的值。
#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
int main()
{
fstream records;
records.open("donation_total.txt", ios_base::in | ios_base::out | ios_base::app);
if (records.is_open())
{
cout << "The record file is open!" << endl;
string line;
while (getline(cin, line))
{
int total = stoi(line);
cout << "Total donation is: "<<total << endl;
cout << "Is there any new record?" << endl;
string str,newname;
stringstream field;
string name;
int donation;
getline(cin , str);
while (str=="Yes" || str=="yes")
{
cout << "Enter name and donation value: ";
getline(cin, newname);
field.str(newname);
field >> name >> donation;
total += donation;
field.clear();
cout << name << " donates " << donation << "$" << endl;
cout << "Total donation is: " << total << endl;
records << endl << total;
cout << "Is there any new record? ";
getline(cin, str);
}
break;
}
}
else
{
cerr << "Could not find the file!" << endl;
}
records.close();
return 0;
}
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