Why my class field is destroyed in constructor - c++

Question

In my constructor I initialize a field. The field is destroyed just after the initialization.
Here's my code and my test:
A.hpp
class A {
private:
T t;
public:
A();
~A();
void add(string name, string num);
};
A.cpp
A::A() {
cout << "Creating A\n";
t = T(100);
cout << "End\n";
}
void A::add(string name, string num) {
cout << "calling add in A\n";
t.add(name, num);
}
T.hpp
class T {
private:
E * t;
public:
T(int size=100);
~T();
void add(std::string name, std::string num);
T.cpp
T::T(int size) : size(size) {
t = new E[size];
}
T::~T() {
cout << "Destroying\n";
// delete[] t; // if I don't comment this I get Segfault when calling add method
}
void T::add(string name, string num){
E e = E(name, num);
t[0] = e;
}
main.cpp
int main(int argc, char* argv[]) {
A a;
a.add("name", "num");
}
Output
Creating A
Destroying
End
calling add in A
Destroying

Answer 1

This code:
t = T(100);
is, equivalently:
T _temp(100);
t = _temp;
Which helps visualize why some T is getting destroyed. It's not your t, it's the temporary T(100). That's why you see two prints of "Destroying"... one for the temporary, and one for A::t.
To avoid the spurious destruction, use an initializer list:
A::A()
: t(100)
{ }