Question

C++ question here. I’ve successfully (after some research :P) created a linked-list implementation for a stack of ints. I’m having some trouble modifying it for char*’s though…

I think it may just be an issue with referenceing/dereferencing pointers in relation to the functions used by the linklistCommands class I have defined below. (I’ve always had trouble understanding when to use & or * in relation to arguments and return values.) I’ve commented the lines in my code that I probably muddled up.

Anyways, here is my code thus far:

struct linkc { // one 'link', stores a pointer to a char array
  char * value;
  linkc *next;
};

class linklistCommands 
{
  public:
    linklistCommands()
      {top = NULL;}
    ~linklistCommands() 
      {}
    void push(char * address) // Pretty sure I'm OK here.
      {
      linkc *temp = new linkc;
      temp->value = address;
      temp->next = top;
      top = temp;
      } 
    char* pop() // Pretty sure I have to change something on this line
      {
      if (top == NULL) 
        return 0;
      linkc * temp;
      temp = top;
      char * value;
      value = temp->value;
      top = temp->next;
      delete temp;
      return value;
      }
    bool isEmpty()
      {
      if (top == NULL) 
        return 1;
      return 0;
      }
  private:
    linkc *top; 
};

int main(void)
{

 // pushed strings are of an arbitrary, but always known, length
 char[4] stringA = "foo"; 
 char[6] stringB = "fooba"; 
 char[8] stringC = "foobar "; 

 linklistCommands commandList;

 commandList.push(stringA);    
 commandList.push(stringB);
 commandList.push(stringC);

 while(commandList.isEmpty!=1)
 {
  cout << (*commandList.pop()) << endl;
 }
}

Thanks for reading through my question and/or any clarification you can provide 🙂

Answer 1

your class seems ok, but the main needs to be changed:

 // pushed strings are of an arbitrary, but always known, length
 char stringA[] = "foo";
 char stringB[] = "fooba";
 char stringC[] = "foobar ";

 linklistCommands commandList;

 commandList.push(stringA);
 commandList.push(stringB);
 commandList.push(stringC);

 while(commandList.isEmpty()!=1)
 {
  cout << commandList.pop() << endl;
 }

You should consider to use std::string instead of char*, it’s easier and safer.
Also, char[N] stringA = “…”; it’s C# or Java syntax, not C++