"If a C++ pointer is deleted twice, it can cause a trap" -- 陷阱是什么意思？

Question

遇到这样一个C++小测验：一个指针被删除两次会怎样？

A) 它可以中止程序
B) 它会导致失败
C) 它可能导致错误
D) 它会造成陷阱

答案是D

我有点迷茫，"trap"是什么意思？它是 C++ 中的一个特殊术语吗？

Answer 1

In computing and operating systems, a trap, also known as an exception or a fault, is typically[NB 1][1] a type of synchronous interrupt typically caused by an exceptional condition (e.g., breakpoint, division by zero, invalid memory access). A trap usually results in a switch to kernel mode, wherein the operating system performs some action before returning control to the originating process. A trap in a system process is more serious than a trap in a user process, and in some systems is fatal. In some usages, the term trap refers specifically to an interrupt intended to initiate a context switch to a monitor program or debugger.

这是高度概括的术语，不是由 C++ 定义的，更不用说特定于它了。更关键的是，你一定要注意选择题中的"can"，因为不能保证你双删一个对象时任何事情都会发生[=13] =]

其实四个答案基本上说的是同一个东西

无论如何，测验似乎很混乱，因为 "deleting a pointer" 可能不是它的意思。

不要与 SNMP 陷阱混淆：

In SNMP, a trap is a type of PDU used to report an alert or other asynchronous event about a managed subsystem.

Answer 2

它在 C++ 中没有任何意义。这可能意味着操作系统级别的错误（例如 Posix 信号），但没有上下文我不能说。

正确答案是它会导致未定义的行为；但是所有的答案都可以被认为是正确的，因为未定义的行为可能会导致这些事情发生。

Answer 3

删除已经删除的相同内存是未定义的行为。任何事情都可能发生，尽管就我而言，它给出了运行时错误。使用 g++ 4.9.1

在 C++ 中编译

我的程序：

int main()
{
    int x = 5;
    int *ptr = &x;
    delete ptr;
    delete ptr;
}

它给出了以下错误：

*** Error in `./t': free(): invalid pointer: 0xbf971994 ***

"If a C++ pointer is deleted twice, it can cause a trap" -- 陷阱是什么意思？

"If a C++ pointer is deleted twice, it can cause a trap" -- what does trap mean?

c++

terminology