C++ 初始化pid_t变量

Valgrind报告了一个错误：

==5644== Conditional jump or move depends on uninitialised value(s)

这种情况发生在类型为

pid\t

的变量上

我的代码如下：

GmpPipePlayer::GmpPipePlayer( IOBase *pIO, Referee *pBack, PieceColor pc, int size, const DataBoard *pBd, int handicap, const char *cmd_line, int bDebug )
    : GmpPlayer(pIO, pBack, pc, size, pBd, handicap, bDebug)
{
    int down[2], up[2];
        pid_t _pid;  //here the var is declared

    pipe(down);   
    pipe(up);


    _pid = fork();

    if (_pid < 0)
        exit(1);


    if (_pid == 0)
    {
        close(down[1]);
        close(up[0]);

        dup2(down[0], 0);
        dup2(up[1], 1);

        execl("/bin/sh", "sh", "-c", cmd_line, NULL);

        _exit(1);
    }

    close(down[0]);
    close(up[1]);
    _down = down[1];
    _up = up[0];

    _reader_thd = new Thread(reader_wrapper, this);
}

GmpPipePlayer::~GmpPipePlayer()
{
    if (_pid > 0)   //valgrind is reporting that the error is here!!
    {
        kill(_pid, SIGTERM);
        _pid = 0;
    }

    if (_up)
    {
        close(_up);
        _up = 0;
    }

    if (_down)
    {
        close(_down);
        _down = 0;
    }   
       delete _reader_thd
}

---

但这仍然会导致同样的错误。这段代码在这个过程中被多次调用。

似乎有两个变量被称为

\u pid

——您在构造函数中声明的本地变量：

pid_t _pid;  //here the var is declared

以及你在析构函数中访问的那个：

if (_pid > 0)   //valgrind is reporting that the error is here!!

这些变量不同：在析构函数中访问的变量必须是全局变量或实例变量（更可能）

由于依赖于

\u pid

将状态从构造函数传递到析构函数，因此需要从构造函数中删除本地声明，并根据需要初始化另一个

\u pid

。如果是实例变量，请将其初始化添加到初始值设定项列表中，如下所示：

GmpPipePlayer::GmpPipePlayer( IOBase *pIO, Referee *pBack, PieceColor pc, int size, const DataBoard *pBd, int handicap, const char *cmd_line, int bDebug )
: GmpPlayer(pIO, pBack, pc, size, pBd, handicap, bDebug), _pid(0) {
    ... //                         HERE ------------------^
}

GmpPipePlayer::GmpPipePlayer( IOBase *pIO, Referee *pBack, PieceColor pc, int size, const DataBoard *pBd, int handicap, const char *cmd_line, int bDebug )
: GmpPlayer(pIO, pBack, pc, size, pBd, handicap, bDebug), _pid(0) {
    ... //                         HERE ------------------^
}