正在移动的 Visual Studio 断点

Question

我最初使用 Visual Studio C++ Express，我已切换到 Ultimate，但我目前对调试器移动断点的原因感到困惑，例如：

if(x > y) {
    int z = x/y;         < --- breakpoint set here
}
int h = x+y;             < --- breakpoint is moved here during run time

或

random line of code      < --- breakpoint set here
random line of code

return someValue;        < --- breakpoint is moved here during run time

它似乎在代码中的随机位置执行此操作。有时我在这里做错了吗？我从来没有遇到过这样的快速版本问题。

Answer 1

您正在发布模式下调试。

if(x > y) {
    //this statement does nothing
    //z is a local variable that's never used
    //no executable code is generated for this line
    int z = x/y;         < --- breakpoint set here
}
//the breakpoint is set on the next executable line
//which happens to be this one
int h = x+y;             < --- breakpoint is moved here during run time

通常调试器会在二进制代码中设置挂钩。如果int z = x/y没有执行二进制代码，则不能在此处设置断点。

以下是在release模式下编译生成的：

if(x > y) 
{
    int z = x/y;//         < --- breakpoint set here
}
int h = x+y;
cout << h;
003B1000  mov         ecx,dword ptr [__imp_std::cout (3B203Ch)] 
003B1006  push        7    
003B1008  call        dword ptr [__imp_std::basic_ostream<char,std::char_traits<char> >::operator<< (3B2038h)]

要对此进行测试，您可以执行以下简单更改：

if(x > y) {
    int z = x/y;
    std::cout << z << endl; // <-- set breakpoint here, this should work
}
int h = x+y;