gistfile1.cpp

#include <iostream>

class Foo {
public:
    Foo() {}

    void say() {
	std::cout << data_ << std::endl;
    }

private:
    int data_;	// uninitialized!
};

int main()
{
    Foo foo;
    foo.say();
    return 0;
}

/*
% cppcheck --enable=all foo.cpp
Checking foo.cpp...
[foo.cpp:5]: (warning) Member variable 'Foo::data_' is not initialized in the constructor.
%
*/