Can't store anything into my arrays - c++

Question

Having trouble storing strings into an array. I tried a multi-dimensional char array but it didn't work. I would ideally like a multi-dimensional string array but every time I try I get the error
cannot convert std::string (*)[100] {aka std::basic_string<char> (*)[100]} to std::string*
Don't even understand what that means. I tried printing the array in my function input_new_student which is where I store the string just to test it, and no luck. The same thing is happening to all my arrays. I've looked it up but I feel like im overlooking something very simple, please help.
#include <iostream>
#include <iomanip>
#include <string>
#include <cstdlib>
#include <ctime>
void print_menu();
int get_selection();
std::string get_Name();
float get_GPA();
int get_Year();
void input_new_student(std::string student_names[], float student_GPA[], int student_start_year[], int index, int ramapo_id[]);
void print_all(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size, int ramapo_id[]);
void print_by_year(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size);
void print_statistics(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size, float sum);
using namespace std;
int main()
{
std::string student_names[100];
float student_GPA[100];
int student_start_year[100];
int ramapo_id[100];
int userChoice;
int index = 0;
int size = 0;
float sum = 0.0;
do
{
print_menu();
userChoice = get_selection();
if (userChoice == 1)
{
input_new_student(student_names, student_GPA, student_start_year, index, ramapo_id);
index++;
}
if (userChoice == 2)
{
print_all(student_names, student_GPA, student_start_year, index, size, ramapo_id);
}
if (userChoice == 3)
{
print_by_year(student_names, student_GPA, student_start_year, index, size);
}
if (userChoice == 4)
{
print_statistics(student_names, student_GPA, student_start_year, index, size, sum);
}
if (userChoice == 5)
{
return 0;
}
} while(userChoice > 0 && userChoice < 4);
return 0;
}
void print_menu()
{
cout << "Please pick from the following menu " << endl;
cout << "1. Add a new student " << endl;
cout << "2. Print all students " << endl;
cout << "3. Print students by year " << endl;
cout << "4. Print student statistics " << endl;
cout << "5. Quit" << endl;
}
int get_selection()
{
int userChoice;
cin >> userChoice;
while (userChoice > 4 || userChoice < 1)
{
cout << "Error: Invalid input, please try again: ";
cin >> userChoice;
}
return userChoice;
}
string get_Name()
{
std::string student_name;
cout << "Please enter the student's name: ";
cin >> student_name;
return student_name;
}
float get_GPA()
{
float student_GPA;
cout << "Please enter the GPA: ";
cin >> student_GPA;
return student_GPA;
}
int get_Year()
{
int student_year;
cout << "Please enter the start Year: ";
cin >> student_year;
return student_year;
}
void input_new_student(std::string student_names[], float student_GPA[], int student_start_year[], int index, int ramapo_id[])
{
//information generation
srand((unsigned)time(0));
int random_integer = rand();
ramapo_id[index] = random_integer;
//information acquisition
student_names[index] = get_Name();
student_GPA[index] = get_GPA();
student_start_year[index] = get_Year();
}
void print_all(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size, int ramapo_id[])
{
for (int i = 0; i < size; i++) {
cout << student_names[i] << " - " << ramapo_id[i] << endl;
}
}
void print_by_year(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size)
{
int student_year_identifier;
cout << "Which year would you like to display?: ";
cin >> student_year_identifier;
for (int i = 0; i < size; i++)
{
if (student_year_identifier == student_start_year[i])
{
cout << "There were " << index << "students in that year" << endl;
}
else {
cout << "There were no students in that year" << endl;
}
}
}
void print_statistics(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size, float sum)
{
cout << "Total: " << index << endl;
float avg = 0.0;
for (int i = 0; i < size; ++i)
{
sum += student_GPA[i];
}
avg = ((float)sum)/size;
cout << "GPA: " << avg << endl;
}

Answer 1

I recommend you have a container of structures rather than multiple containers:
struct Student_Info
{
std::string name;
double gpa;
unsigned int starting_year;
}
typedef std::vector<Student_Info> Student_Info_Container;
Student_Info_Container database;
// You could also have an array of student information:
static const size_t MAXIMUM_STUDENTS = 32U;
Student_Info_Container student_information[MAXIMUM_STUDENTS];
Placing the information into a structure support encapsulation and makes the program more efficient.
With parallel arrays, there is a possibility of synchronization issues. For example, the GPA for student 3 may be at index 4 of the array.
If you are restricted to arrays, you would only need to pass 2 parameters to your functions, the array and the capacity of the array.

Answer 2

There are few issues with your code, e.g.:
Your code is difficult to debug because you are using infinite while loops while taking input (e.g. in main and get_selection function).
How would you know if your code is working? At least, print something which indicates that your code is working, like cout << "Student added suuccessfully"; in input_new_student function.
I made these above mentioned changes and you can see that (at least) your code is working for option 1 at http://ideone.com/D5x8Eh
PS: I didn't get that compilation error, you should mention the compiler and flags you are using.

Answer 3

So as an update, the reason I wasn't able to print my array was begin I was not incrementing in my for loop. Thanks to #milesbudnek , #dreschjerm. I was able to see that my code was actually printing by adding the messages, this was prior to the suggestions, but thanks for the suggestion. Here is the code as it is now. Currently I just need to find a way to find values in the array (which I will search for) and create the multi-dimensional array for the strings.
#include <iostream>
#include <iomanip>
#include <string>
#include <cstdlib>
#include <ctime>
void print_menu();
int get_selection();
std::string get_Name();
float get_GPA();
int get_Year();
void input_new_student(std::string student_names[], float student_GPA[], int student_start_year[], int index, int ramapo_id[]);
void print_all(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size, int ramapo_id[]);
void print_by_year(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size);
void print_statistics(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size, float sum);
using namespace std;
int main()
{
std::string student_names[100];
float student_GPA[100];
int student_start_year[100];
int ramapo_id[100];
int userChoice;
int index = 0;
int size = 0;
float sum = 0.0;
//seed
srand((unsigned)time(0));
do
{
print_menu();
userChoice = get_selection();
if (userChoice == 1)
{
input_new_student(student_names, student_GPA, student_start_year, index, ramapo_id);
index++;
size++;
}
if (userChoice == 2)
{
print_all(student_names, student_GPA, student_start_year, index, size, ramapo_id);
}
if (userChoice == 3)
{
print_by_year(student_names, student_GPA, student_start_year, index, size);
}
if (userChoice == 4)
{
print_statistics(student_names, student_GPA, student_start_year, index, size, sum);
}
if (userChoice == 5)
{
return 0;
}
} while(userChoice > 0 && userChoice < 5);
return 0;
}
void print_menu()
{
cout << "Please pick from the following menu " << endl;
cout << "1. Add a new student " << endl;
cout << "2. Print all students " << endl;
cout << "3. Print students by year " << endl;
cout << "4. Print student statistics " << endl;
cout << "5. Quit" << endl;
}
int get_selection()
{
int userChoice;
cin >> userChoice;
while (userChoice > 5 || userChoice < 1)
{
cout << "Error: Invalid input, please try again: ";
cin >> userChoice;
}
return userChoice;
}
string get_Name()
{
std::string student_name;
cout << "Please enter the student's name: ";
cin >> student_name;
return student_name;
}
float get_GPA()
{
float student_GPA;
do {
cout << "Please enter the GPA: ";
cin >> student_GPA;
} while(!(student_GPA < 4.0 && student_GPA > 0.0));
return student_GPA;
}
int get_Year()
{
int student_year;
do {
cout << "Please enter the start Year: ";
cin >> student_year;
} while(!(student_year > 1972 && student_year < 2015));
return student_year;
}
void input_new_student(std::string student_names[], float student_GPA[], int student_start_year[], int index, int ramapo_id[])
{
//information generation
int random_integer = rand()%900000 + 100000;
ramapo_id[index] = random_integer;
//information acquisition
student_names[index] = get_Name();
student_GPA[index] = get_GPA();
student_start_year[index] = get_Year();
//Notification
cout << endl;
cout << "The student with R# " << random_integer << " was created." << endl;
cout << endl;
}
void print_all(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size, int ramapo_id[])
{
cout << endl;
for (int i = 0; i < size; i++) {
cout << student_names[i] << " - " << ramapo_id[i] << endl;
}
cout << endl;
}
void print_by_year(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size)
{
int student_year_identifier;
//to trigger the response that there ARE students in that year
bool trigger;
int student_count = 0;
cout << "Which year would you like to display?: ";
cin >> student_year_identifier;
for (int i = 0; i < size; i++)
{
if (student_start_year[i] == student_year_identifier)
{
bool trigger = true;
student_count++;
}
}
if (trigger = true) {
cout << endl;
cout << "There are " << student_count << " student(s) in that year" << endl;
cout << endl;
}
else {
cout << endl;
cout << "There are no students in that year." << endl;
cout << endl;
}
}
void print_statistics(std::string student_names[], float student_GPA[], int student_start_year[], int index, int size, float sum)
{
//Print Total
cout << "Total: " << index << endl;
//Print GPA average
int smart_kids = 0;
float avg = 0.0;
for (int i = 0; i < size; ++i)
{
sum += student_GPA[i];
}
avg = ((float)sum)/size;
cout << "GPA: " << std::setprecision(3) << avg << endl;
//Print # of students above 2.0
for (int i = 0; i < size; i++)
{
if (student_GPA[i] > 2.0)
{
smart_kids++;
}
}
cout << "Above a 2.0: " << smart_kids << endl;
}