11 How to DEBUG C++ in Visual Studio

Breakpoints and reading memory

Setting breakpoints to read memory

1. Breakpoints

A breakpoint is a point in the program where the debugger will break (interrupt). When execution reaches the line with the breakpoint, the execution thread will pause.

Visual Studio Breakpoint Shortcut: F9

When Debugging, make sure you are in "Debug" mode. The configuration can be seen in Configuration. In "Release" mode, the code may be altered, and your breakpoints might never be executed. ^a1059f

Debugging

Step Into: F11

Step Over: F10

Step Out: Shift + F11

Now, perform a Step into on the seventh line of the main function.

The yellow arrow indicates that the current line has not been executed yet. Press F10 to move the arrow to the sixth line. After pressing F10 again, the string is output.

Look at this program:

int main()
{
·   int a = 8;   //breakpoint
    a++;
    const char* string = "Hello";

    for (int i = 0; i < 5; i++)
    {
        const char c = string[i];
        std::cout << c << std::endl;
    }

    Log("Hello Wolrd");
    std::cin.get();
}

At this point, int a=8 has not been executed yet, and it is still uninitialized memory.

Memory View

^dd3537

During debugging, you can bring up the memory view by navigating to Debug->Windows->Memory->Memory1 in the top navigation bar.

Enter &a to access the memory address of variable a, which is displayed in hexadecimal.

Why is it all cc?

This indicates that it is uninitialized stack memory.

Press F10.

You can see that the data stored in memory has changed. Every two hexadecimal digits represent one byte.

If I want to exit the loop, pressing Step Out will exit the entire function. So, I just need to set another breakpoint and press F5 to run to the breakpoint.