It is not a good practice using stl-classes in the dll-interface as Common practice in dealing with warning c4251: class … needs to have dll-interface explains. An example is given:
#include <iostream>
#include <string>
#include <vector>
class __declspec(dllexport) HelloWorld
{
public:
HelloWorld()
{
abc.resize(5);
for(int i=0; i<5; i++)
abc[i] = i*10;
str="hello the world";
}
~HelloWorld()
{
}
std::vector<int> abc;
std::string str;
};
When compiling this file, the following warnings can be observed:
warning C4251: 'HelloWorld::str' : class 'std::basic_string<_Elem,_Traits,_Ax>' needs to have dll-interface to be used by clients of class 'HelloWorld'
warning C4251: 'HelloWorld::abc' : class 'std::vector<_Ty>' needs to have dll-interface to be used by clients of class 'HelloWorld'
Then the question is how we can implement the same functionality without using STL class vector and string. One implementation I could think of is as follows:
class __declspec(dllexport) HelloWorld2
{
public:
HelloWorld2()
{
abc_len = 5;
p_abc = new int [abc_len];
for(int i=0; i<abc_len; i++)
p_abc[i] = i*10;
std::string temp_str("hello_the_world");
str_len = temp_str.size();
p_str = new char[str_len+1];
strcpy(p_str,temp_str.c_str());
}
~HelloWorld2()
{
delete []p_abc;
delete []p_str;
}
int *p_abc;
int abc_len;
char *p_str;
int str_len;
};
As you can see, in the new implementation we use int *p_abc to substitute vector abc and char *p_str to replace string str. The question I have is whether there are other elegant implementation approaches that can do the same. Thanks!