else if looping quandry - c++

Question

I am in the second phase of a project where I need to extend my program into a menu driven application to query the database I have on a .txt file. So, my trouble is that I cannot get my loop to be perpetual. It always terminates when it initializes from one option to the next. Here is the snippet of my code that is my int main:
int main ()
{
char Q,q;
char S,s;
char task;
string pathname;
string z;
int count=0;
cout << "Welcome to Jason Rodriguez's Library Database." << endl;
cout << "Please enter the name of the backup file: ";
cin >> pathname;
ifstream inFile(pathname.c_str());
while(!inFile.eof())
{
getline(inFile,z);
count++;
}
while (task != 'Q' || task != 'q') {
cout << count << " records loaded successfully." << endl;
cout << "Enter Q to (Q)uit, Search (A)uthor, Search (T)itle, (S)how All: ";
cin >> task;
if ((task == 'Q')||(task =='q'))
{
cout << "Program will now terminate";
break;
}
else if ((task == 'S')||(task =='s'))
{
showAll (loadData (pathname));
cout << endl;
cout << "Enter Q to (Q)uit, Search (A)uthor, Search (T)itle, (S)how All: ";
cin >> task;
}
}
}
I need to add two more options into the loop on top of these two but I figured I should get the first two working correctly first. The other two should be plug & chug after that. Basically what I was trying to do is say if the user enters Q or q, terminate the program. Else, if user hits S or s, activate showall function and after ward, go back to the original query. It isn't working though. Assistance is welcome and appreciated.

Answer 1

Menus almost always require loops - especially ones that require the user to enter the correct choice input. The most applicable one in a case like this is the while loop - but essentially, any other loop variant can be used.
UPDATE:
int main ()
{
char task;//this is the only char needed. Your other chars were redundant
string pathname;
string temp;//I changed z to temp to better reflect its purpose
int count=0;
cout << "Welcome to Jason Rodriguez's Library Database." << endl;
cout << "Please enter the name of the backup file: ";
cin >> pathname;
ifstream inFile(pathname.c_str());//this is potentially a problem in that you aren't verifying that the pathname is a valid one
//you did not check to see that your file was open, otherwise there is no way to tell that you successfully opened the file
if (inFile.is_open()) {
//while(!inFile.eof()) is a character by character read and comparison
//made your life easier by shortening it down to this - which ensures
//that a line is read. (Much faster and more readable)
while(getline(inFile,temp))
{
count++;
}
inFile.close();//always close a file after you've used it
//At this point the entire file has been read. So, this is where this message SHOULD be
cout << count << " records loaded successfully." << endl;
}
else {
//if there was an error opening the file (i.e. wrong path, or it simply does not exist), this will be displayed
cout << "There was a problem opening your file" << endl;
exit(0);//and the program will terminate
}
while (task != 'Q' || task != 'q') {
cout << "Enter Q to (Q)uit, Search (A)uthor, Search (T)itle, (S)how All: ";
cin >> task;
if ((task == 'Q')||(task =='q'))
{
cout << "Program will now terminate";
break;
}
else if ((task == 'S')||(task =='s'))
{
string author;
//showAll (loadData (pathname));
cout << endl;
cout << "Search an Author" << endl;
cin >> author;//get the author name to search from the user
//write code to search an author here
}
}
}
There are a number of issues with the code that you posted which I will forgo for the sake of brevity. Hence, note the following:
Your code was printing the same message per option (except for quit). Of course it would appear that it didn't work. Each option is a different task. Print what each task does (similar to what I did).
You wish to search the file for an author, but you have not stored it. Look into a way of storing it that appeases your instructor.
It would be ideal for you to use switch in this case, considering the increasing complexity of your code.
Try breaking down each task into functions, and call them to make your main function readable. In fact, it is a good programming practice for your main function to be as small as possible.
And, as juanchopanza quite rightly pointed out: you have some fundamental issues with C++. Try doing some more exercises and do more examples from a good C++ book.