Checking user valid input and compare with the text file - c++

Question

I have a system where it will display a menu option for user to select and do certain action. Currently I am facing an issue on the function changepassword.
When users select the option of changing password, it will read into my text file and display all the users stored in the text file.
Then users are prompted to enter the user ID that they wish to edit. I am able to edit the records and store back into the text file. But I encounter an issue when the user initially entered a user ID that is not found in the text file. The system should show an error message and go back to the menu bar.
The checks are okay in the removeuser() function when the users enter an invalid user ID, the system will go back to menu bar, but not for changepassword().
//Main Function
int main()
{
switch(option)
case 1:
.....
break;
case 2:
....
break;
case 3:
changepassword();
break;
default break;
}
//Edit user information
void changepassword()
{
printer.printcpheader();
displayuserid(); //display list of user ID to select
string id;
cout<<" enter Cashier ID to edit :"; //getting input
cin>>id;
cout<<endl;
int i = getuserindex(id);
displayuserinfobyid(i); //display selected user ID information
string cashierID;
string password;
cout<<"";
getline(cin, cashierID);
cout<<" Cashier ID :";
getline(cin, cashierID);
cout<<" Password :";
getline(cin, password);
//storing to array
users[i].cashierID = cashierID;
users[i].pw = Decrypt(password);
writeUserDatabase();
cout<<"\E[1;32m"<<cashierID<<" info edited !!!\E [0m"<<endl;
}
//Store values to txt file
void writeUserDatabase()
{
ofstream outfile;
outfile.open ("userdatabase.txt");
if (!outfile)
{
cout << "\E[1;31mFile opened for writing failed\E[0m" << endl;
}
for(int i=0;i<MAX-1; i++) // get the index of array to be display out
{
if(users[i].cashierID!="")
{
outfile<<users[i].cashierID<<";";
outfile<<users[i].pw<<endl;
}
}
outfile.close();
}
//Display all user info
void displayuserinfobyid(int id,int k)
{
//printout selected id information, with highlighting
int i=id;
if(i!=-1)
{
if(k==1)
{
cout<<" User ID :\E[1;32m"<<users[i].cashierID<<"\E[0m"<<endl;
}
else if(k==2)
{
cout<<" User ID :"<<users[i].cashierID<<endl;
}
}
else
{
cout<<" \E[1;31mNo such User ID...\E[0m"<<endl;
}
}
//Get the index from user array
int getuserindex(string id)
{
int i=-1;
for(int i=0;i<MAX-1; i++) // get the index of array to be display out
{
if(users[i].cashierID==id)
{
return i;
}
}
return i;
}
//Remove user info
void removeuser()
{
printer.printruheader();
cout<<endl;
displayuserid(); //display list of User ID to select
string selectedid;
cout<<" enter username to remove :"; //getting input
cin>>selectedid;
cout<<endl;
int i = getuserindex(selectedid);
displayuserinfobyid(i); //display selected user ID information
if(i!=-1)
{
cout<<" are you sure you want to remove (Y/N) :"; //confirmation
char yesno;
cin>>yesno;
yesno = toupper(yesno);
if(yesno=='Y')
{
users[i].cashierID = "";
cout<<" \E[1;29mUser ID "<<selectedid<<" deleted...\E[0m"<<endl;
writeUserDatabase(); //update userdatabasefile
}
else
{
cout<<" \E[1;31mDelete Fail...\E[0m"<<endl;
}
}
}

Answer 1

If the problem is you want to return from the function "changePassword" after an incorrect ID was submitted, then you can just use return; as the function's return type is void.
Notice there are 3 possibilities : return, break or exit.
Break is used to break out of a loop or a switch.
For example :
for(int i = 0; i < 10; ++i) {
if(i < 5)
cout << i << endl;
else
break; // Will cause the loop to be executed 5 times only
}
Exit can be used to force the program to stop execution.
Return is used whenever you just want to return from the current function, this expects something to be returned except if the return type is void.