SDL SDL_DisplayFormat c++ pointer retunes NULL on vaild images - c++

Question

simple code the image pointer are NULL why?:
// defined in the header files
SDL_Surface* m_imageIcon;
SDL_Surface* m_CharMainTile;
bool SDLmanager::loadFiles()
{
m_imageIcon = loadImage("D:\\java\\workspace\\SDL_test1\\Debug\\robot1.bmp",type_bmp);
/*
mem print as you see empty
Name : m_imageIcon
Details:0x0
Default:0x0
Decimal:0
Hex:0x0
Binary:0
Octal:0
*/
m_CharMainTile = loadImage("D:\\java\\workspace\\SDL_test1\\Debug\\vx_chara09_d.png",type_png);
bool b = false;
if(m_imageIcon == NULL) // this is null
b = true;
if(m_CharMainTile == NULL) // this is null
b = true;
if(!b)
return false;
return true;
}
this is where i set the files there all vaild and in the given path
SDL_Surface *SDLmanager::loadImage( string filename , imgType t)
{
//Temporary storage for the image that's loaded
SDL_Surface* loadedImage = NULL;
//The optimized image that will be used
SDL_Surface* optimizedImage = NULL;
//Load the image
if(t== type_bmp)
{
loadedImage = SDL_LoadBMP( filename.c_str() );
}
else
{
loadedImage = IMG_Load( filename.c_str() );
}
//If nothing went wrong in loading the image
if( loadedImage != NULL )
{
//Create an optimized image
optimizedImage = SDL_DisplayFormat( loadedImage );
//Free the old image
SDL_FreeSurface( loadedImage );
}
//Return the optimized image
return optimizedImage;
}
optimizedImage has vaild address and value
Name : optimizedImage
Details:0x4d6ea8
Default:0x4d6ea8
Decimal:5074600
Hex:0x4d6ea8
Binary:10011010110111010101000
Octal:023267250
compilation is fine and clean :
make all
Building file: ../Main.cpp
Invoking: GCC C++ Compiler
g++ -O0 -g -Wall -c -fmessage-length=0 -MMD -MP -MF"Main.d" -MT"Main.d" -o "Main.o" "../Main.cpp"
Finished building: ../Main.cpp
Building file: ../SDLmanager.cpp
Invoking: GCC C++ Compiler
g++ -O0 -g -Wall -c -fmessage-length=0 -MMD -MP -MF"SDLmanager.d" -MT"SDLmanager.d" -o "SDLmanager.o" "../SDLmanager.cpp"
Finished building: ../SDLmanager.cpp
Building target: SDL_test1.exe
Invoking: MinGW C++ Linker
g++ -o "SDL_test1.exe" ./Main.o ./SDLmanager.o -lmingw32 -lSDL_image -lSDLmain -lSDL
Finished building target: SDL_test1.ex