invincibility frame and take damage class - c++

Question

i am a beginner and i have already read a doc but i need to practice for learn and now i am stuck.
So i would like to do a class takeDommage for apply a number of dmg and activate a countdown for create the invincibility frame.
so i tryed this (see code under)
It's the first class i create alone so i don't understand what's wrong
main :
if(Collision::PixelPerfectTest(sprite_perso,sprite_ennemis))
{
std::cout<<"collision pp"<<std::endl;
takeDommage::prendreDegat(10);
std::cout<<pv<<std::endl;
}
takeDommage.h :
#ifndef TAKEDOMMAGE_H
#define TAKEDOMMAGE_H
#include <SFML/Graphics.hpp>
#include <string>
#include <iostream>
#include <cstdlib>
#include <cmath>
class takeDommage
{
public:
takeDommage();
prendreDegat(int Dommage);
//virtual ~takeDommage();
protected:
sf::Clock takeDammageClock;
int Dommage;
private:
};
#endif // TAKEDOMMAGE_H
takeDommage.cpp
#include "takeDommage.h"
takeDommage::takeDommage()
{
}
void takeDommage::prendreDegat(int Dommage)
{
if(takeDammageClock.getElapsedTime().asSeconds()>=3)
{
std::cout << "bite" << std::endl;
pv -= Dommage;
takeDammageClock.restart();
}
}
error:
||=== Build: Debug in TheGameSFML (compiler: GNU GCC Compiler) ===|
E:\Work\Top_secret\code\TheGame\main.cpp||In function 'int main()':|
E:\Work\Top_secret\code\TheGame\main.cpp|168|warning: comparison between signed and unsigned integer expressions [-Wsign-compare]|
E:\Work\Top_secret\code\TheGame\main.cpp|180|warning: comparison between signed and unsigned integer expressions [-Wsign-compare]|
E:\Work\Top_secret\code\TheGame\main.cpp|217|error: cannot call member function 'int takeDommage::prendreDegat(int)' without object|
E:\Work\Top_secret\code\TheGame\main.cpp|156|warning: unused variable 'enemySpawnTimer' [-Wunused-variable]|
E:\Work\Top_secret\code\TheGame\src\takeDommage.cpp|8|error: prototype for 'void takeDommage::prendreDegat(int)' does not match any in class 'takeDommage'|
include\takeDommage.h|15|error: candidate is: int takeDommage::prendreDegat(int)|
||=== Build failed: 3 error(s), 3 warning(s) (0 minute(s), 0 second(s)) ===|

Answer 1

you seem to be very new in c++. the compiler already telling you what's wrong with it.
error: cannot call member function 'int takeDommage::prendreDegat(int)' without object|
you need to instantiate (create) your object first. the way you accessing as if the takeDommage function is a static function which is not. its public a member function of takeDamage
assuming that you have instantiated your takeDommage class somewhere before the if statement call,
TakeDommage Obj;
...
...
if(Collision::PixelPerfectTest(sprite_perso,sprite_ennemis))
{
std::cout<<"collision pp"<<std::endl;
Obj.prendreDegat(10); //calling the prendredegat member function of Obj
std::cout<<pv<<std::endl;
}
in addition to that you are missing the return type void before the function name of prendreDegat
class takeDommage
{
public:
takeDommage();
//prendreDegat(int Dommage); //missing void
void prendreDegat(int Dommage); //correct way. which can be translated as Prendredegat returns nothing.