[解決済み】c++でプログラム実行時にヒープが破壊されたエラーが発生する。

質問内容

以下のプログラムを持っていますが、実行するたびに時々（ほとんどの場合）ヒープ破壊のエラーが発生します。

実行するたびにプログラムの別の場所にポップするので、どこで起こっているのか指をくわえて見ていることはできません。

どなたか、この問題を解決する方法を教えてください。

P.S ヒープ破壊は、私がpを解放しようとしているときにもポップアップします。

ありがとうございました。

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

using namespace std;
const int MAX_OF_PLAYERS = 10;
const int SIZE = 100;

struct player_t {
    char *name;
    int numOfShirt;
};
struct team_t {
    char *nameOfTeam;
    int maxOfPlayers;
    int numOfPlayers;
    player_t *players;

};

void readPlayer(player_t *player);
void initTeam(team_t *team);
void addPlayer(team_t *team);
void printTeam(team_t *team);
void freeAll(team_t *team);
player_t** getAllPlayersStartWithA(team_t *team);
void printAteam(player_t **p);

int main()
{
    team_t t;
    player_t **p;
    initTeam(&t);
    addPlayer(&t);
    addPlayer(&t);
    printTeam(&t);
    p = getAllPlayersStartWithA(&t);
    if (p[0] != NULL)
        printAteam(p);
    system("pause");
    freeAll(&t);
    //delete[] p;
}

void readPlayer(player_t *player)
{
    char name[SIZE];
    cout << " please enter the name of the player " << endl;
    cin >> name;
    cout << " please enter the num of the shirt " << endl;
    cin >> player->numOfShirt;
    int size = strlen(name);
    char *res = new char[size + 2];
    strcpy(res, name);
    player->name = res;
}
void initTeam(team_t *team)
{

    char name[SIZE];

    // get the team name
    cout << " please enter your team name" << endl;
    cin >> name;
    // get the name length
    int size = strlen(name);
    // allocate new array with length size
    team->nameOfTeam = new char[size + 1];
    // copy the string to the new array
    strcpy(team->nameOfTeam, name);

    // get the number of max players
    cout << "please enter the number of the max players on your team" << endl;
    cin >> team->maxOfPlayers;

    // create new players array
    player_t *players = new player_t[team->maxOfPlayers];
    // initial the players array
    for (int i = 0; i < team->maxOfPlayers; i++)
    {
        players[i] = { 0 };
    }
    //bind the array to team
    team->players = players;

    // set current players to 0
    team->numOfPlayers = 0;

}
void addPlayer(team_t *team)
{

    for (int i = 0; i < team->maxOfPlayers; i++)
    {
        if (team->players[i].name == NULL)
        {
            readPlayer(team->players + i);
            break;
        }
    }

}
void printTeam(team_t *team)
{

    cout << "Team name: ";
    cout << team->nameOfTeam << endl;

    cout << "Max Number of players in team: ";
    cout << team->maxOfPlayers << endl;

    cout << "Current number of players in team: ";
    cout << team->numOfPlayers << endl;

    cout << "Team Players:" << endl;
    for (int i = 0; i < team->maxOfPlayers; i++)
    {
        if (team->players[i].name)
        {
            cout << "Player name: ";
            cout << team->players[i].name;
            cout << ", ";
            cout << "Player shirt: ";
            cout << team->players[i].numOfShirt << endl;
        }
    }
    cout << endl;
}
void freeAll(team_t *team)
{
    for (int i = 0; i < team->maxOfPlayers; i++)
    {
        if ((team->players + i)->name != NULL)
            delete[](team->players + i)->name;
    }

    delete[] team->players;
}
player_t** getAllPlayersStartWithA(team_t *team)
{
    int sum = 0, position = 0;
    for (int i = 0; team->players[i].name != NULL; i++)
    {
        if (team->players[i].name[0] == 'a' || team->players[i].name[0] == 'A')
        {
            sum++;
        }
    }

    player_t **p = new player_t*[sum + 1];

    for (int i = 0; i < team->maxOfPlayers; i++)
    {
        p[i] = NULL;
    }

    for (int i = 0; team->players[i].name != NULL; i++)
    {
        if (team->players[i].name[0] == 'a')
        {
            p[position++] = team->players + i;
        }
    }
    return p;
}
void printAteam(player_t **p)
{
    cout << "Players start with 'A': " << endl;
    for (int i = 0; p[i] != NULL; i++)
    {
        cout << "Player name: ";
        cout << (p[i]->name);
        cout << ", ";
        cout << "Player shirt: ";
        cout << (p[i]->numOfShirt) << endl;
    }
}

解決方法は？

私はコード全体をレビューしたわけではありませんが、このような状況で役に立つ、メモリの使用状況を追跡し、何か問題が発生した場合に表示するツールがあります。その一例が、少なくともLinux環境では利用可能なvalgrindです。とにかく、このツールを使って、あなたのコードに少なくとも1つのバグを以下のように見つけることができました。

1. デバッグ情報を入れてコンパイルする。gccを使用している場合は、-gコマンドラインフラグを使用します。

   g++ foo.cpp -g -o foo -std=gnu++11
   
   

2. valgrindで実行する

   valgrind ./foo
   
   

3. 出力を見る

   ==6423== Memcheck, a memory error detector
   ==6423== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
   ==6423== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
   ==6423== Command: ./foo
   ==6423== 
    please enter your team name
   sdfads
   please enter the number of the max players on your team
   3
    please enter the name of the player 
   efwf
    please enter the num of the shirt 
   5
    please enter the name of the player 
   dsfdsa
    please enter the num of the shirt 
   3
   Team name: sdfads
   Max Number of players in team: 3
   Current number of players in team: 0
   Team Players:
   Player name: efwf, Player shirt: 5
   Player name: dsfdsa, Player shirt: 3
   
   ==6423== Invalid write of size 8
   ==6423==    at 0x4011FF: getAllPlayersStartWithA(team_t*) (foo.cpp:155)
   ==6423==    by 0x400C08: main (foo.cpp:38)
   ==6423==  Address 0x5ab6668 is 0 bytes after a block of size 8 alloc'd
   ==6423==    at 0x4C2E80F: operator new[](unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
   ==6423==    by 0x4011CC: getAllPlayersStartWithA(team_t*) (foo.cpp:151)
   ==6423==    by 0x400C08: main (foo.cpp:38)
   ==6423== 
   ==6423== 
   ==6423== HEAP SUMMARY:
   ==6423==     in use at exit: 72,719 bytes in 3 blocks
   ==6423==   total heap usage: 8 allocs, 5 frees, 74,829 bytes allocated
   ==6423== 
   ==6423== LEAK SUMMARY:
   ==6423==    definitely lost: 15 bytes in 2 blocks
   ==6423==    indirectly lost: 0 bytes in 0 blocks
   ==6423==      possibly lost: 0 bytes in 0 blocks
   ==6423==    still reachable: 72,704 bytes in 1 blocks
   ==6423==         suppressed: 0 bytes in 0 blocks
   ==6423== Rerun with --leak-check=full to see details of leaked memory
   ==6423== 
   ==6423== For counts of detected and suppressed errors, rerun with: -v
   ==6423== ERROR SUMMARY: 2 errors from 1 contexts (suppressed: 0 from 0)
   
   

4. この出力によると、どうやら155行目に問題があるようです。

   ==6423== Invalid write of size 8
   ==6423==    at 0x4011FF: getAllPlayersStartWithA(team_t*) (foo.cpp:155)
   
   

   そして、よく見ると、次のようになっています。

   player_t **p = new player_t*[sum + 1];
   for (int i = 0; i < team->maxOfPlayers; i++)
   {
        p[i] = NULL;
   }
   
   

   sum+1サイズの配列を作成しますが、team->maxOfPlayersまで反復処理します。これは、変更したい配列の外側のメモリに書き込むことになり、ヒープ内の書き込んではいけない場所に書き込むことになります（ヒープ破壊につながります）。

これは少なくとも1つの問題点です。valgrindが他に文句を言うことがなくなるまで、1.-4.を繰り返してください。