c++ code to put user input into a textfile

Question

I am new to C++ and I would like some help with creating a function that adds expenses into a text file. This is what would be inside of the text file?

Type of Expenses:Amount:Date

Listed below is an example of the code I am using but I get an error saying that too few arguments to function void addExpense(char,int,int) .

Here's the code I am using:

#include <iostream>
#include <fstream>

using namespace std;

void addExpense(char expense, int amount, int date){
     cout << "Type of Expense: " << endl;
     cin >> expense;
     cout << "Amount: " << endl;
     cin >> amount;
     cout << "Date: " << endl;
     cin >> date;
}

int main(int argc, char** argv) {
     addExpense();
     return 0;
} 

Answer 1

According to declaration, the method addExpense() accepts 3 arguments:

void addExpense(char expense, int amount, int date);

But while calling, you are passing 0 argument:

addExpense();

Instead, do this:

addExpense(expense, amount, date);

But, in main() since you do not have any variables, do this:

void addExpense(char expense, int amount, int date){
     //implement the logic to write to file
}

int main(int argc, char** argv) {
     char expense;
     int amount, date;
     cout << "Type of Expense: " << endl;
     cin >> expense;
     cout << "Amount: " << endl;
     cin >> amount;
     cout << "Date: " << endl;
     cin >> date;
     addExpense(expense, amount, date);
     return 0;
}

Answer 2

You need to provide the arguments:char expense, int amount, int date.

For example:

#include <iostream>
#include <fstream>

using namespace std;

void addExpense(char expense, int amount, int date){
     cout << "Type of Expense: " << endl;
     cin >> expense;
     cout << "Amount: " << endl;
     cin >> amount;
     cout << "Date: " << endl;
     cin >> date;
}

int main(int argc, char** argv) {

     char expense;
     int amount;
     int date;

     addExpense(expense, amount, date);
     return 0;
}

Answer 3

According to function declaration, the method addExpense() accepts 3 arguments:

void addExpense(char expense, int amount, int date);

But in the function calling, you are passing 0 argument:

addExpense();

Instead, try this:

char expense = e; int amount = 50, int date = 20150119; addExpense(expense, amount, date);

Answer 4

I think the main thrust of the question (beyond the compiler error) goes towards how to write into or rather append to a text file.

The mechanism typically used to interact with files is a filestream (here: ofstream = output-filestream). Try adding a filename argument to your addExpense() function like this (and since you read the variables from user input inside the function, I would also declare them there and not make them arguments):

void addExpense(const std::string& filename);

and add the following code inside the function:

void addExpense(const std::string& filename){
 //local variable declarations (no need to pass them):
 char expense;
 int amount;
 int date;

 //user input
 cout << "Type of Expense: " << endl;
 cin >> expense;
 cout << "Amount: " << endl;
 cin >> amount;
 cout << "Date: " << endl;
 cin >> date;

 //new: append a line to the file
 std::ofstream out(filename, ios::append);
 out << expense << ":" << amount << ":" << date << std::endl;
 out.close();  //important for making sure that everything is actually written to file ("flush" the stream)!
}

The function is then called like this:

addExpense("c:/myfile.txt");