how to detect or avoid using C++ uninitialized pointer? [closed] - c++

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I got an uninitialized pointer problem today. unfortunately, it caused core dump after it released.
here is the sample code, and the function print_request() is new code, and this function could be used by several other functions:
// def.h
struct INFO {
uint32_t val1;
uint32_t val2;
};
struct INFO_LIST {
uint32_t id;
struct INFO * data;
};
// util.cpp
void print_request(const struct INFO_LIST req)
{
fprintf(stdout, "%u\t%u\t%u\n", req.id, req.data->val1, req.data->val2);
}
// A.cpp
int parse_ie(...)
{
// ...
struct INFO_LIST req;
req.id = 10;
req.data = new INFO();
req.val1 = 101;
req.val2 = 102;
print_request(req);
// ...
}
// B.cpp
int parse_chrome(...)
{
// ...
struct INFO_LIST req;
req.id = 20;
print_request(req); // core dump here!
// ...
}
here is what I have done:
I have wroten the unit test for print_request(), but I forgot there is an uninitialized pointer while function parse_chrome() use it.
I analyzer the code by using the static code analyzer tool, for example, cppcheck, and there is no error or warning.
it is still ignored after code reviewing.
so, I want to know:
is there any good tool to detect the uninitialized pointer in C++?
how to avoid using uninitialized pointer in C++?
any suggestion would be appreciated, thank you!
PS, I want to write uniform functions to call the pointer, but it would cost much time.
PPS. sorry, variable "req" is not a pointer. my fault.

Answer 1

First, add a default constructor to INFO_LIST:
struct INFO_LIST {
uint32_t id;
struct INFO * data;
INFO_LIST() : id(0), data(nullptr) { ; }
};
Second: Throw an exception in print_request:
// util.cpp
void print_request(const struct INFO_LIST req)
{
if (! req.data->val1 || ! req.data->val2)
throw (std::runtime_error ("Uninitialized pointers"));
fprintf(stdout, "%u\t%u\t%u\n", req.id, req.data->val1, req.data->val2);
}
If you want to catch this at compile time:
struct INFO_LIST {
uint32_t id;
struct INFO * data;
INFO_LIST (struct INFO* d) : data(d) { ; }
private:
INFO_LIST () { ; }
};
Now you will get an error at compile time if you try to construct an INFO_LIST without initializing the data pointer.

Answer 2

You have created a struct pointer at line INFO_LIST * req;, remove a * to create a struct instead. Currently you are using a bare pointer (of type struct INFO_LIST) to nothing.

Answer 3

How avoid using a c++ empty pointer?
Your code looks like c, to me. The languages are different, pick one or the other.
As to your question title:
In C++, you can use the non-nullptr value tested as:
if(ptr) ptr->doSomething();
else doSomethingElse();
NOTE that pointers are POD, and must be explicitly initialized.
So
MyObject* ptr = new MyObject; // default ctor
assert(nullptr != ptr); // check for success
or
MyObject* ptr = nullptr;
// later code sets the pointer to something
I prefer to use the slightly more clear:
if(nullptr != ptr) ptr->doSomething();