gdb watchpoint on struct variables

Question

I have a structure like this : ``` struct A { int a; char b; }; ``` this structure is referenced at various places in a large code. The pointer to this struct is passed on to different functions and accordingly the variables in this structure are updated. i want to set a watchpoint on variable a in this struct as it travels across many functions. to see how a changes. How do I set this watch point ?

Accepted Answer

First set a breakpoint where you create an instance of your struct using break, like

```
break myfile.c:9
```

Then just use watch to set a watchpoint, like

```
watch myStructInstance.a
```

for variable a or

```
watch *0x7ffff75177f0
```

for a memory address. The memory address can be obtained easily by using print, like

```
print &myStructInstance.a
```

Now every time variable a or the given memory address gets modified gdb will break.

gdb watchpoint on struct variables

Solution

Problem