I will present 2 solutions one without advanced C++ and the second will make use of the STL and structs.
Solution 1 (The old school way):
Solution without using advance C++ or STL (comments in the code will explain each step):
#include <iostream>
using namespace std;
// utility function to swap two elements
template<typename T>
void swap(T *xp, T *yp)
{
T temp = *xp;
*xp = *yp;
*yp = temp;
}
// we can do better sorting algorithm than this but its the simplest
void bubbleSort(double speeds[], string names[], int n)
{
for (int i = 0; i < n-1; i++) {
for (int j = 0; j < n-i-1; j++) {
if (speeds[j] < speeds[j+1]){ // if current elements is lower than the next one
swap(&speeds[j], &speeds[j+1]); // swap speeds
swap(&names[j], &names[j+1]); // swap names
}
}
}
}
int main()
{
int number;
cout << "How many do you have? ";
cin >> number;
string* names = new string[number];
double* speeds = new double[number];
cout << "Enter the names and speeds (name 'space' speed): " << endl;
for (int i = 0; i < number; i++)
{
cin >> names[i] >> speeds[i]; // here its i not number (number is out of range)
// this array goes from 0 to number - 1
}
bubbleSort(speeds, names, number); // call sorting algorithm O(n*n)
cout << "resutls = " << endl;
for (int i = 0; i < number; i++) // print resutls out
cout << "Name : " << names[i] << " Speed: " << speeds[i] << endl;
// free the memory we allocated from the heap (Never forget this)
delete[] names;
delete[] speeds;
return 0;
}
Solution 2 (STL + Structs):
First of all, since the name and speed are coupled together you might need to put them in a
so-called struct which is a package that will put your (name, speed) data together.
There is alternative to this, you might want to use std::pair but since you want your data to be sorted later by ascendant speed we will stick to the struct and define the operator< which will be useful later for sorting.
// We pack our data inside one struct that contain the name and the speed
struct NameSpeed
{
string name;
double speed;
bool operator < (const NameSpeed& other) const // we need to define this operator for sorting
{
return (speed < other.speed); // sort based on speed field
}
};
Now since we are getting input from user which imply that the size of the array is not defined during compile time we might need to use dynamic memory.
STL (C++ Standard Library) offers std::vector which is array allocated dynamically and have the ability to resize so its really flexible and safer to use than new and delete operators.
Finally here is the code that you need with comments to clarify each step:
#include <iostream>
#include <vector> // we need this for the vector class which is like an array
#include <algorithm> // we need this to sort the array later
using namespace std;
// We pack our data inside one struct that contain the name and the speed
struct NameSpeed
{
string name;
double speed;
bool operator < (const NameSpeed& other) const // we need to define this operator for sorting
{
return (speed < other.speed);
}
};
int main()
{
int i,number;
cout<<"How many do you have? ";
cin>> number;
vector<NameSpeed> items(number); // resize our array to have number as
// size ( better than NameSpeed items[number];
// which is allocated on the stack and we need dynamic memory
// and vector manage this for us)
cout<<"Enter the names and speeds (name 'space' speed): ";
cout<<endl;
// Please note that vector class have the operator[]
// which allow us to use it just like a normal array
for (i = 0; i < number; i++) // iterate
{
cin >> items[i].name >> items[i].speed; // get the data from the user name, speed respectively
}
cout<<endl;
sort(items.begin(), items.end()); // sort our array based on speed
for (const NameSpeed& ns : items) // Iterate through our array
cout << "Name :" << ns.name << "Speed :" << ns.speed << endl; // print name speed respectively
return 0;
}
