C ++无法识别.h声明

Question

I've got the following functions declared in creature.h (under public):

void _hop();
void _turn(size_t way);
void _infect();
Point _facing();
bool _isEmpty();
bool _wall();
bool _same();

Then their implementation in the .cc (I've deleted a bunch of code for shortness):

void Creature::_hop(){
 CODE
}

Point Creature::_facing(){
  CODE
}

void Creature::_infect(){
  CODE
}

bool Creature::_isEmpty(){
 CODE
}

bool Creature::_wall(){
 CODE
}

bool Creature::_same(){
 CODE
}

But then upon compile I get these errors:

creature.cc:25: error: no 'void Creature::_hop()' member function declared in class 'Creature'
creature.cc:54: error: no 'void Creature::_turn(size_t)' member function declared in class 'Creature'
creature.cc:88: error: no 'geometry::Point Creature::_facing()' member function declared in class 'Creature'
creature.cc:105: error: no 'void Creature::_infect()' member function declared in class 'Creature'
creature.cc:114: error: no 'bool Creature::_isEmpty()' member function declared in class 'Creature'
creature.cc:121: error: no 'bool Creature::_wall()' member function declared in class 'Creature'
creature.cc:127: error: no 'bool Creature::_same()' member function declared in class 'Creature'

tons of other functions are getting read fine but these ones aren't getting any love. ?????

EDIT:

Not sure about the down votes, probably because you guys are assuming that I didn't either a) include it in the creature class or b) #include "creature.h". I did both, just didn't include that in the question since I thought that was obvious.

EDIT 2: You want .cc and .h? Oh dear lord.

CREATURE.H:

 #ifndef CREATURE
 #define CREATURE
 class Creature {
  public:
   // Constructor (note there is no need for a destructor.)
   Creature();
   Creature(Species *species,World *world,Point pt,Direction d);    

   // takeOneTurn executes lines of this creature's species program,
   // beginning on programLine and continuing until a HOP, LEFT, RIGHT, or 
   // INFECT is executed.
   void takeOneTurn();

   // getters and setters do the obvious things.
   Species *getSpecies();
   Direction getDirection();
   // use this to initialize and infect.  It also sets programLine to 1. 
   void setSpecies(Species * s); 
   void _hop();
   void _turn(size_t way);
   void _infect();
   Point _facing();
   bool _isEmpty();
   bool _wall();
   bool _same();

  private:
   Species *species;   // pointer to this creature's species
   World *world;       // a pointer to the world in which this 
                       // creature is located.
   Point loc;          // where in the world this creature is located
   Direction dir;      // current direction this creature is facing
   size_t programLine; // current program line  
 };

 #endif

CREATURE.CC

 #include "creature.h"
 #include <cstdlib>

 Creature::Creature(Species *s, World *w,Point pt,Direction d){
   world = w;
   species = s;
   loc = pt;
   dir = d;
   programLine = 0;
 }


 Species* Creature::getSpecies(){
   return species;
 }

 Direction Creature::getDirection(){
   return dir;
 }

 void Creature::setSpecies(Species* s){
   species = s;
 }

 void Creature::_hop(){
   switch(dir){
   case NORTH:
     if(!world->getContents(Point(loc.col,loc.row+1))){
       world->setContents(loc, NULL);
       world->setContents(Point(loc.col,loc.row+1), this);
     }
     break;
   case SOUTH:
     if(!world->getContents(Point(loc.col,loc.row-1))){
       world->setContents(loc, NULL);
       world->setContents(Point(loc.col,loc.row-1), this);
     }
     break;
   case EAST:
     if(!world->getContents(Point(loc.col+1,loc.row))){
       world->setContents(loc, NULL);
       world->setContents(Point(loc.col+1,loc.row), this);
     }
     break;
   case WEST:
     if(!world->getContents(Point(loc.col-1,loc.row))){
       world->setContents(loc, NULL);
       world->setContents(Point(loc.col-1,loc.row), this);
     }
     break;
   }
 }

 void Creature::_turn(size_t way){
   if(way == 0){
     switch(dir){
     case NORTH:
       dir = WEST;
       return;
     case WEST:
       dir = SOUTH;
       return;
     case SOUTH:
       dir = EAST;
       return;
     case EAST:
       dir = NORTH;
       return;
     }
   } else {
     switch(dir){
     case NORTH:
       dir = EAST;
       return;
     case WEST:
       dir = NORTH;
       return;
     case SOUTH:
       dir = WEST;
       return;
     case EAST:
       dir = SOUTH;
       return;
     }
   }
 }

 Point Creature::_facing(){
   switch(dir){
   case NORTH:
     return Point(loc.col,loc.row+1);
     break;
   case WEST:
     return Point(loc.col-1,loc.row);
     break;
   case SOUTH:
     return Point(loc.col,loc.row-1);
     break;
   case EAST:
     return Point(loc.col+1,loc.row);
     break;
   }
 }

 void Creature::_infect(){
   Point facing = _facing();
   if(!world->inRange(facing))return;
   Creature* enemy = world->getContents(facing);
   if(!enemy) return;
   enemy->setSpecies(species);
   world->setContents(facing, enemy);
 }

 bool Creature::_isEmpty(){
   Point facing = _facing();
   if(!world->inRange(facing))return false;
   if(!world->getContents(facing)) return true;
   return false;
 }

 bool Creature::_wall(){
   Point facing = _facing();
   if(!world->inRange(facing))return true;
   return false;
 }

 bool Creature::_same(){
   Point facing = _facing();
   if(!world->inRange(facing))return true;
   if(!world->getContents(facing)) return false;
   Creature* enemy = world->getContents(facing);
   return (enemy->species == species);
 }

 bool _random(){
   int k =  random();
   return (k%2);
 }

 void Creature::takeOneTurn(){
   Instruction whatToDo = species->programStep(programLine);
   switch(whatToDo.op){
   case HOP:
     _hop();
     programLine++;
     break;
   case LEFT:
     _turn(0);
     programLine++;
     break;
   case RIGHT:
     _turn(1);
     programLine++;
     break;
   case INFECT:
     _infect();
     programLine++;
     break;
   case IFEMPTY:
     if(_isEmpty()){
       programLine = whatToDo.line;
       takeOneTurn();
     }
     break;
   case IFWALL:
     if(_wall()){
       programLine = whatToDo.line;
       takeOneTurn();
     }
     break;
   case IFSAME:
     if(_same()){
       programLine = whatToDo.line;
       takeOneTurn();
     }
     break;
   case GO:
     programLine = whatToDo.line;
     takeOneTurn();
     break;
   case IFRANDOM:
     if(_random()) programLine = whatToDo.line;
     else programLine++;
     takeOneTurn();
     break;
   }
 }

Phew!

Answer 1

What you have described should work fine, so we have to assume that your description doesn't quite match reality.

Specifically, the following code compiles and runs fine.

pax$ cat creature.h
class Creature {
    public:
        void _hop();
};

pax$ cat creature.cc
#include <iostream>
#include "creature.h"

void Creature::_hop() {
    std::cout << "Hop\n";
}

int main (void) {
    Creature c;
    c._hop();
    return 0;
}

pax$ rm creature ; g++ -o creature creature.cc ; ./creature
Hop

Since that transcript shows what you seem to be doing, my advice is to post your actual code for analysis, including the full header file and almost full source file (you can leave in the CODE markers since they won't affect this particular problem but it would be useful to see things like the include statements and so forth).

The best problem reports should come with:

• the expected behaviour.
• the actual behaviour.
• a small complete program that exhibits the errant behaviour.

---

Based on your code updates (and assuming they're complete), you have the problem that size_t , Species , World , Point and Direction are not actually defined before you include creature.h in your creature.cc file.

This is causing the creation of the Creature class to fail on the second constructor so that it doesn't know about that class. Then, when you try to define the actual code for said class, the compiler (rightly) complains that it doesn't exist.

When I add a very small main to your code and try to compile, I get these header file problems:

In file included from creature.cc:1:
creature.h:5: error: expected `)' before '*' token
creature.h:13: error: ISO C++ forbids declaration of 'Species' with no type
creature.h:13: error: expected ';' before '*' token
creature.h:14: error: 'Direction' does not name a type
creature.h:16: error: 'Species' has not been declared
creature.h:18: error: 'size_t' has not been declared
creature.h:20: error: 'Point' does not name a type
creature.h:26: error: ISO C++ forbids declaration of 'Species' with no type
creature.h:26: error: expected ';' before '*' token
creature.h:27: error: ISO C++ forbids declaration of 'World' with no type
creature.h:27: error: expected ';' before '*' token
creature.h:29: error: 'Point' does not name a type
creature.h:30: error: 'Direction' does not name a type
creature.h:31: error: 'size_t' does not name a type

which are caused by those non-definitions.

Then I see the sort of errors you describe, such as:

creature.cc:129: error: 'world' was not declared in this scope
creature.cc:129: error: 'facing' was not declared in this scope
creature.cc:130: error: 'world' was not declared in this scope
creature.cc:130: error: 'facing' was not declared in this scope
creature.cc:131: error: 'world' was not declared in this scope
creature.cc:131: error: 'facing' was not declared in this scope
creature.cc:132: error: 'class Creature' has no member named 'species'
creature.cc:132: error: 'species' was not declared in this scope

(just a sample of the many pages of output).

You need to ensure that you have included the header files which define those types before including creature.h . Ideally, creature.h would do this itself rather than relying on whatever is using it to do it.

size_t can be found in <cstring> , the others need to be found by yourself. For example, placing:

#include <cstring>
typedef int Species;
typedef int World;
typedef int Point;
typedef int Direction;

at the top of your header file gets rid of all those errors - it introduces a bucketload of other errors since the typedef statements are wrong but I'm just illustrating what you need to do here.

Find out where those other things are defined and include them, along with <cstring> , at the top of creature.h .

Answer 2

It looks like you're trying to write a class. You have to put the function declarations in a class declaration, then include the header in the source file.

Creature.h

class Creature {
private: // assuming these are private functions
    void _hop();
    void _turn(size_t way);
    void _infect();
    Point _facing();
    bool _isEmpty();
    bool _wall();
    bool _same();

}; // don't forget the ;

Creature.cc

#include "Creature.h"

... your original Creature.cc  contents ...

If you're not writing a class but a series of free functions, remove the Creature:: from your function names in Creature.cc .

Answer 3

Your header file says that the functions are standalone, but your source file says they belong to the "Creature" class. At the very minimum, you need to either:

• surround your declarations with a struct or class

  struct Creature { ....your function declarations... };

or

• Remove the Creature:: from your cpp file.

Finally, starting function names with an undescore is bad practice. Don't do it.

Answer 4

Just before

class Creature {

try adding the following:

#error The class declaration for Creature is indeed being compiled

And see if that generates an error. If not, then I suspect something went wrong with your header guard.

Your header guard macro name should be longer than just CREATURE . It's too easy for a CREATURE macro to be accidentally defined somewhere else (like in a library) and messing up your header guard. If the name of your project is, say, "Monster Mash", then your header guard for creature.h should be something complicated like: MONSTER_MASH_CREATURE_H or MONSTER_MASH_CREATURE_INCLUDE . That way, it's extremely improbable that someone else has already defined your header guard macro.

Answer 5

Move #include "creature.h" to the TOP of the list of includes in your creature.cc file. Then, fix the compile errors (types 'Point', etc. not defined), and try again. The creature.h file needs to include or forward-declare all the types it uses, or you get weird problems.

I also second the suggestion to put a #error just above the Creature class declaration, to ensure that CREATURE didn't somehow get defined elsewhere (and thus force the class declaration to be skipped). And you might want a more unique header on your header file -- my own convention would have been _CREATURE_H_

Anyway, the upshot is that most of these kinds of bugs are caused by problems somewhere else, and the symptoms are only distantly related to the reason. C++, alas, is loaded with these kinds of gotchas.