Cannot find a way to define my functions..

[kl2eativ]

I have a big function problem. I am trying to make a program that writes the user input to a file until the user inputs '*'. Then closes the file, reopens it and displays whatever it has written to it.. I tried to compile it so i can test it but i get and error in the while loop. I need help defining my functions. Here is what my code looks like so far..

//This program will create and display the contents of a text file.

#include <iostream>
#include <fstream>
using namespace std;

//Prototypes
void UserInput();
void WritetoFile();
void ReopenFile();
void CloseFile();
int PerformCalc();


const char asterisk = '*';

int main(){ 
    struct Inventory {
    int inventoryNumber, markup;
    string itemDescription;
    double unitCost; };
  
//Calling functions
UserInput();
return 0;
}    

//***********************************
//Defining UserInput                *
//***********************************
 UserInput()
  while (Inventory != asterisk)
  }       
   cout << "Enter Inventory number";
   cin>> inventoryNumber;
   cout << "Enter Item Description";
   cin>> itemDescription;
   cout << "What is the Unit Cost?";
   cin>> unitCost;
   cout << "What is the Markup percent?";
   cin>> markup;
   WritetoFile()
   else{
        CloseFile()
        cout << "Done inputing data";
        
   }
//***********************************
//Defining WritetoFile              *
//***********************************
fstream writefile;
writefile.open("PRODUCT.TXT");

//***********************************
//Defining CloseFile                *
//***********************************
fstream closefile;
closefile.close("PRODUCT.TXT");
//***********************************
//Defining ReopenFile               *
//***********************************
ifstream reopenfile;
reopenfile.open("PRODUCT.TXT");
PerformCalc()
reopenfile >> inventoryNumber;
reopenfile >> itemDescription;
reopenfile >> unitCost;
reopenfile >> markup;

//***********************************
//Defining PerformCalc               *
//***********************************

[Zhuge]

You have some brace errors. Functions need to open with {, and close with }. All other { need to also be matched with a }. You also need to include the return type of your functions in your implementation as well.