You never declared getgrundflaeche before calling it. The compiler assumes undeclared functions return int. The later function definition is, of course, different. Solve this by adding a declaration before main():
You’re defining the class in the header file, include the header file into a *.cpp file and define the class a second time because the first definition is dragged into the translation unit by the header file. But only one gameObject class definition is allowed per translation unit. You actually don’t need to define the … Read more
You need header guards on that header file. It is presumably being included twice. Modify the header, adding these lines to the beginning and end. The define doesn’t need to be STUDENT_H… it just needs to be unique. With these directives added, the compiler will ignore all contents of the header file if it has already been parsed. … Read more
You’re defining the class in the header file, include the header file into a *.cpp file and define the class a second time because the first definition is dragged into the translation unit by the header file. But only one gameObject class definition is allowed per translation unit. You actually don’t need to define the … Read more