C++ swap function with array of records - c++

Question

I have just started to learn C++ and have been working on a few problems to hone my skills. Currently I am having a problem swapping some values of my array of records. The input validation works fine but then when I try to swap the values around the program stops responding and crashes. Here is how I have created it:
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int grandprixnum;
struct DriverData {
string driver;
int car;
string team;
int grid;
int points;
};
DriverData * grand = new DriverData[grandprixnum];
int input()
{
cout << "How many drivers where there? ";
cin >> grandprixnum;
cin.sync();
DriverData * grand = new DriverData[grandprixnum];
for (int i=0; i<grandprixnum; i++)
{
cout << "Driver numbers: "<< i+1 << " \n";
cout << "What is the drivers name? \n";
getline (cin, grand[i].driver);
cin.sync();
cout << "What is the drivers car number? \n";
cin >> grand[i].car;
while (grand[i].car > 99 || grand[i].car < 1)
{
cout << "Please enter a value between 1 and 99! \n";
cin >> grand[i].car;
}
cin.sync();
cout << "What team is the driver racing for? \n";
getline (cin, grand[i].team);
cin.sync();
cout << "What grid are they in? \n";
cin >> grand[i].grid;
cin.sync();
while (grand[i].grid < 0 || grand[i].grid > 22)
{
cout << "Please enter a grid number between 1 and 22! \n";
cin >> grand[i].grid;
}
cin.sync();
cout << "What are their total points? \n";
cin >> grand[i].points;
cin.sync();
while (grand[i].points > 25 || grand[i].points < 0)
{
cout << "Please enter the drivers points between 0 and 25! \n";
cin >> grand[i].points;
}
}
}
int sorting ()
//This part _______________________________
{
for(int a=1; a<=grandprixnum; a++)
{
for(int b=0; b<=grandprixnum; b++)
{
if(grand[b].points < grand[b+1].points)
{
swap(grand[b].driver, grand[b+1].driver);
swap(grand[b].car, grand[b+1].car);
swap(grand[b].team, grand[b+1].team);
swap(grand[b].grid, grand[b+1].grid);
swap(grand[b].points, grand[b+1].points);
}
}
}
}
//To here_________________________________
int showtable ()
{
cout << "Driver Car Team Grid Points \n";
for(int c=0; c<grandprixnum; c++)
{
cout << grand[c].driver << grand[c].car << grand[c].team << grand[c].grid << grand[c].points << "\n";
}
}
int main()
{
input ();
sorting ();
showtable ();
}
I have looked around and cannot find an example or someone having the same problem as me. If someone could show me what is wrong with it. Thank you in advance.
EDIT: I have tested the swap before and it does work but it seems to struggle with the array of records.

Answer 1

You access to your array out of bounds. Your array has a length of grandprixnum so you can access to elments from 0 to grandprixnum-1
for(int a=1; a < grandprixnum; a++)
// ^
{
for(int b=0; b < grandprixnum-1; b++)
// ^ ^^ -1 because of b+1
{
if(grand[b].points < grand[b+1].points)
{
...
}
}
}
If ter is nothing to return in a function you dont need a return type. Use void sorting(), void input(), void showtable()
You declareted your array grand twice. On time global and second time local in function input. Declare it global and allocate it in function input.
DriverData * grand = NULL;
int input()
{
...
grand = new DriverData[grandprixnum];

Answer 2

Remove equal sign from this line:
for(int b=0; b<=grandprixnum; b++)
So it will be like this:
for(int b=0; b<grandprixnum; b++)
And replace this line
DriverData * grand = new DriverData[grandprixnum];
with
grand = new DriverData[grandprixnum]; // will store in global variable