Re: stl map error error C2440
* swtsvn:
hey all,
I am attempting to use map with VC 2005. where i need to map one
integer value to another integer
for e.g 2:5
4:5
the actual use is to map a common int value with direct input values.
here is the code
SN_Input.cpp
//initializes the map
void SN_Input::init_keymap(){
It's generally ungood to have separate initialization routines. But how to avoid
that depends on your concrete program.
//vector
vector<int>* vec=new vector<int>;
vec->push_back(KEYBOARD_PARAM::LEFT_ARROW);
vec->push_back(DIK_LEFT);
You don't have to dynamically allocate a vector.
And in fact you have a memory leak here because you decided to allocate the
vector dynamically.
Anyway, the vector is not needed.
keyMap=new map<int,int>();
keyMap->insert(vec->begin(),vec->end());
Most probably keyMap doesn't need to be dynamically allocated any more than the
vector above.
When keyMap directly is a 'map<int, int>' all of the above code, since the start
of the routine, reduces to
keyMap[KEYBOARD_PARAM::LEFT_ARROW] = DIK_LEFT;
}
// function to see if a key is pressed or not, called from a different
file game.cpp
bool SN_Input::isKeyPressed(int key){
int value=keyMap[KEYBOARD_PARAM::LEFT_ARROW];
if(fDIKeyboardState[value] & 0x80){
return TRUE;
}
return FALSE;
}
Don't use 'TRUE' and 'FALSE' when C++ has perfectly good 'true' and 'false'. But
don't use 'true' and 'false' either. Just use a boolean expression.
When keyMap directly is a 'map<int, int>' you can write the above as
bool SN_Input::isKeyPressed( int )
{
return !!(fDIKeyboardState[keyMap[KEYBOARD_PARAM::LEFT_ARROW] & 0x80);
}
But it seems to me that the function argument should be used for something, or
there should be no argument?
it gives me the following error:
1>c:\users\suja\documents\visual studio 2005\projects\sujatha-ase-
project\sujatha-ase-project\sn_input.cpp(197) : error C2440:
'initializing' : cannot convert from 'std::map<_Kty,_Ty>' to 'int *'
1> with
1> [
1> _Kty=int,
1> _Ty=int
1> ]
1> No user-defined-conversion operator available that can
perform this conversion, or the operator cannot be called
Please see the FAQ item about how to post a question about Code That Does Not Work.
Those who read your article do not know what line 197 of your code is.
Cheers & hth.,
- Alf