Question

I get the following errors with my code.

cannot convert parameter 1 from ‘std::string’ to ‘char *

no operator found which takes a right-hand operand of type ‘const char *

Can someone tell me what I’m doing wrong in the menuSelection function below? The point of it is if a user selects 1 from the menu options, the program gets user input (lastName, firstName, courseName, letterGrade) and passes it to the addRecord function but I think my data types are off.

Sorry for the long post. The menuSelection function is towards the bottom right about the main() and head() functions.

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>

using namespace std;

   
void GradeBook::addRecord(char* lastName, char* firstName, char* className, char letterGrade)
{
    StudentRecord* newRecord = new StudentRecord(lastName, firstName, className, letterGrade);
    if (_headRecord == NULL) {
        _headRecord = newRecord;
    } else { 
        int compare = _headRecord->compareTo(lastName, firstName);
        if (compare < 0) {
            // we insert before the first element
            newRecord->setNext(_headRecord);
            _headRecord = newRecord;
        } else {
            _headRecord->insert(newRecord);
        }
    }
}

  void menuSelection(int selection, GradeBook& gradeBook) {

    string firstName;
    string lastName;
    string courseName;
    char letterGrade;

    switch(selection) {
        case 1: cin >> lastName.c_str() >> firstName.c_str() >> courseName.c_str() >> letterGrade;
                gradeBook.addRecord(lastName, firstName, courseName, letterGrade);
        case 4: gradeBook.read("students.txt");
                gradeBook.displayAllRecords();
                break; 
        case 5: gradeBook.write("students1.txt");
                break; 
        default: cout << "Enter a valid choice.\n"; 
        } 

        if (selection != 5) {
            displayMenu();
            cin >> selection; 
            menuSelection(selection, gradeBook);
        }
} 

void header() {
    cout << "STUDENT GRADEBOOK AND GPA CALCULATOR\n";
    cout << "=====================================\n";
}

void main()
{
    GradeBook gradeBook;

    int userSelection;
    header();
    displayMenu();
    cin >> userSelection; // get the user input for menu selection
    menuSelection(userSelection, gradeBook);
    
    char pause;

    std::cin >> pause;
}

Answer 1

cin >> lastName.c_str() >> firstName.c_str() >> courseName.c_str()
    >> letterGrade;

I don’t think you really want to do that. c_str() is to turn a regular C++ std::string into an old C-style “string” for use with functions that expect such a beast.

If you’re trying to input a regular C++ string, you should change that to:

cin >> lastName >> firstName >> courseName >> letterGrade;

In fact, unless you’re using the C library part of C++ (or third-party functions which explicitly requires C “strings”), you should never need to use a char * style of string. Embrace the language and use std::string as much as possible.