要一致观察并偶尔检查gdb当前帧之外的变量 [英] Want to watch consistently and examine occasionally the variable outside the current frame in gdb

问题描述

假设我在主函数中定义了一个名为 var 的变量。我设置了一个观察点。然后我输入另一个名为 func（）的函数。目前，观察点可能会被删除，因此我无法访问该变量。任何方法都可以随时保持观察点？

另外，我知道我可以使用类似的语法print main :: var 打印出变量的值。但这还不够。任何好主意？

解决方案

gdb的奇怪之处在于 watch 尝试尊重表达的所有组成部分的范围。因此，如果您监视var ，并且 var 超出范围，则移除观察点。这也适用于更复杂表达式的元素，例如 watch a + b 。

这有一个理由，当然，在某种程度上有点酷 - 但它很少是你真正想要的。根据我的经验，更为正常的做法是不去关心范围，只想看一些内存。

为此，请将 -location 添加到 watch 命令。这将会执行你更常用的操作 - 只需要表达式引用的内存。因此， watch -location var 。

Say I define a variable named varin the main function. And the I set a watchpoint to it. Then I enter another function called func(). At this time, the watchpoints may be deleted so that I have no access to that variable. Any method to make to possible to always keep the watchpoint whenever you are?

Also, I know I can use syntax like print main::var to print out the value of the variable. But that is not sufficient enough. Any good idea?

解决方案

An oddity of gdb is that watch tries to respect the scope of all the constituent parts of the expression. So, if you watch var, and var goes out of scope, the watchpoint is removed. This applies to the elements of a more complicated expression as well, like watch a + b.

This has a justification, of course, and is sort of cool in a way -- but it is rarely what you actually want. It's far more normal, in my experience, not to care about the scope and to just want to watch some bit of memory.

To do this, pass -location to the watch command. This will do what you more commonly want to do -- just want the memory referred to by the expression. So, watch -location var.

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