while 循环中的奇怪错误 (C++)

Question

I'm trying to make a program that works with a simple algorithm.

But for some reason, I get a strange bug (below is the simplified version of the program).

#include "stdafx.h"
#include <iostream>
#include <string>

using std::cout;
using std::string;

void find(int arr[], string name)
{
    int t = 8;
    int i = 0;
    int v = 0;

    // t should become equal to the smallest int of the array after this.


    while (arr[i])
    {
        if (arr[i] < t)
        {
            t = arr[i];
        }
        ++i;
    }

    /* When this statement below gets executed t gets what looks like a                 
    random value for some reason */
    cout << arr[t] << '\n';
    for (int b = 0; b < 2; ++b)
    {
        if (t == arr[b])
        {
            v = b;
        }
    }

    /* Again, arr[v] gets what looks like a random number */
    cout << "The cheapest " << name << " is number " << arr[v] << ".";
}



int main()
{

    /* [0] = "Cost for Steve"
       [1] = "Cost for Mark"
       [2] = "Cost for Andrew" */

    int cleaning[] = { 5, 4, 7 };
    int cooking[] = { 3, 6, 4 };
    int babysitting[] = { 7, 6, 3 };

    cout << "Number 1: Steve, Number 2: Mark, Number 3: Andrew.\n";

    find(cleaning, "cleaner");
    find(cooking, "cook");
    find(babysitting, "babysitter");




/* This is to prevent the console application from quitting */

    while (true)
    {

    }

}

I'm sure there is something wrong in the for and the while loop, but what?

If you're reading my code and some text or variable name seems foreign to you, chances are that I forgot to translate it (this is originally written in Italian).

Thanks for taking your time to read this.

EDIT: Thanks to @Tar I fixed the first part of the program, but the part which says The (name) that costs less is n. (arr[v]). The (name) that costs less is n. (arr[v]). still gives me a random number, I compiled and ran the program, the output is:

Number 1: Steve, Number 2: Mark, Number 3: Andrew.
4
The cheapest cleaner is number 4.
3
The cheapest cook is number 3.
3
The cheapest babysitter is number 7.

That is obviously wrong as it should say that the cheapest cleaner is number 2, the cheapest cook is number 1 and the cheapest babysitter is number 3.

PS: As soon as everything is fixed I will take the part which prints the cheapest price out.

Answer 1

The problem is within your first while loop in find :

while (arr[i]) // while the element at arr[i] is NOT 0
{
    if (arr[i] < t)
    {
        t = arr[i];
    }
    i++;
}

Here you continuously evaluate elements in arr for whether they are not 0 . This is not correct. You've declared your arrays as:

int cleaning[3] = { 5, 4, 7 };
int cooking[3] = { 3, 6, 4 };
int babysitting[3] = { 7, 6, 3 };

None of these contain 0 , so your while loop will run indefinitely and you'll be reading past the memory for each array which is not good news.

Consider using std::vector instead, and see how much clearer and safer your code becomes:

#include <vector>
#include <iostream>

void find(const std::vector<int>& numbers)
{
    auto t = 8;
    // Look through each element in the container:
    for(auto number : numbers)
    {
        if (number < t)
        {
            t = number;
        }
    }
    std::cout << t << std::endl;
}

int main()
{
    std::vector<int> cleaning = {5, 4, 7};
    find(cleaning);
}

Answer 2

Above all, I want to make a statement: I am not an English-speaker, so if I said wrong words, please excuse me.
I think this question is not very difficult. I fixed your algorithm and output format. Actually, I almost rewrote it.
In my view, your code seems kind of naive. If you only learnt C++ syntax, there is a long way to study algorithm.

#include <iostream>
#include <string>
#include <vector>
using namespace std;

int find(const vector<int>& numbers) {
    int minVul = numbers[0];
    int rank = 0;

    for (int i = 1; i < numbers.size(); i++)
    {
        if (minVul > numbers[i])
        {
            minVul = numbers[i];
            rank = i;
        }
    }
    return rank;
}



int main() {

    vector<string> name = { "steve","mark","andrew" };
    /* [0] = "Cost for steve"
    [1] = "Cost for mark"
    [2] = "Cost for andrew" */

    vector<int> cleaning = { 5, 4, 7 };
    vector<int> cooking = { 3, 6, 4 };
    vector<int> babysitting = { 7, 6, 3 };

    int cleaner = find(cleaning);
    cout << "Cleaning:" << name[cleaner] << " costs least in " << cleaning[cleaner] << endl;
    int cooker = find(cooking);
    cout << "Cooking:" << name[cooker] << " costs least in " << cooking[cooker] << endl;
    int babysitter = find(babysitting);
    cout << "Babysitter:" << name[babysitter] << " costs least in " << babysitting[babysitter] << endl;

    system("pause"); //This is a common skill to prevent the console application from quitting.
    return 0;
}

Outputs:

Cleaning:mark costs least in 4
Cooking:steve costs least in 3
Babysitter:andrew costs least in 3