Stacks Question

[muran_pling]

Hi guys, just wondering how i would remove an unwanted string element from a string stack.

Example:

void remove_string(stack <string>& string_stack, string unwanted);

int main()
{
    stack <string> S;

    string X = "Bob";
    string Y = "Bye";
    string T = "Hi";
    string U = "Hello";

   S.push(X);
   S.push(Y);
   S.push(T);
   S.push(U);
    
    
system("PAUSE");
return 0;
}

void remove_string(stack <string>& string_stack, string unwanted)
{

}

much appreciated!

[JVene]

From some of the STL documentation from one vendor:

A template container adaptor class that provides a restriction of functionality limiting access to the element most recently added to some underlying container type. The stack class is used when it is important to be clear that only stack operations are being performed on the container.

What this means is that unless pushing or popping is enough, you should choose another container that has the feature of removing elements in the interior.

[muran_pling]

From some of the STL documentation from one vendor:




What this means is that unless pushing or popping is enough, you should choose another container that has the feature of removing elements in the interior.

what if it asks to use stack container?

[Desolation]

Use a temporary stack.

while current element is not the one you are looking for
  push the last element of the first stack on the second stack
  remove the last element of the first stack
end while

if the size of the first stack is now 0
  push the last element of the second stack on the first
  remove the last element of the second stack
else
  remove the last element of the first stack (the element you were looking for)
  while the size of the second stack is different of 0
    push the last element of the second stack on the first stack
    remove the last element of the second stack
  end while
end if

[muran_pling]

Use a temporary stack.

while current element is not the one you are looking for
  push the last element of the first stack on the second stack
  remove the last element of the first stack
end while

if the size of the first stack is now 0
  push the last element of the second stack on the first
  remove the last element of the second stack
else
  remove the last element of the first stack (the element you were looking for)
  while the size of the second stack is different of 0
    push the last element of the second stack on the first stack
    remove the last element of the second stack
  end while
end if

this is what i came up with.. my code doesnt seem to be working now..

void remove_string(stack <string>& string_stack, string unwanted)
{
     stack <string> temp_stack;
     
     string W = "dont";
     string X = "you";
     string Y = "why";
     string Z = "high";
     
     
     unwanted = "high";
     
     
     string_stack.push(W);
     string_stack.push(X);
     string_stack.push(Y);
     string_stack.push(Z);
     
     
     cout<<string_stack.size();
     cout<<endl;
     
     
    
    while(!string_stack.top()==unwanted)
     {
        temp_stack.push(string_stack.top());        
        string_stack.pop();                   
     }
     
     
     if(string_stack.size()==0)
     {
       string_stack.push(temp_stack.top());
       temp_stack.pop();
     }
     else
     {
       string_stack.pop();
        while(!temp_stack.size()==0)
        {
         string_stack.push(temp_stack.top());
         temp_stack.pop();
        }
     }
     cout<<endl;
     cout<<string_stack.size();

}

any ideas?

[Desolation]

Define "not working". I'm not guessing your problems. Sorry.

Edit: Bahh.. I'm feeling generous. I'll tell you that you are missing parentheses. Think operator precedence.

[muran_pling]

Define "not working". I'm not guessing your problems. Sorry.

Ok well, its actually only removing the last string. Its not removing the unwanted string.

[Desolation]

void remove_string(stack <string>& string_stack, string unwanted)
{
     // ...
    while(!string_stack.top()==unwanted)
     {
        temp_stack.push(string_stack.top());        
        string_stack.pop();                   
     }
     
     
     if(string_stack.size()==0)
     {
       //...
     }
     else
     {
       string_stack.pop();
        while(!temp_stack.size()==0)
        {
         //...
        }
     }
     //...

}

[muran_pling]

Define "not working". I'm not guessing your problems. Sorry.

Edit: Bahh.. I'm feeling generous. I'll tell you that you are missing parentheses. Think operator precedence.

hehehe hrmmmm, this will take forever to figure out .. ill get there! thanks heaps anyway man. appreciate the help

Edit: Ohhhh the exclamation mark must go in front of the equals sign ? and i put an extra equals sign...

[Desolation]

I've told you you had missing parentheses, I told you to look for operator precedence and I've even highlighted the two faulty lines.. ' ! '

[Desolation]

void remove_string(stack <string>& string_stack, string unwanted)
{
     // ...
    while(string_stack.top()!=unwanted)
     {
        temp_stack.push(string_stack.top());        
        string_stack.pop();                   
     }
     
     
     if(string_stack.size()==0)
     {
       //...
     }
     else
     {
       string_stack.pop();
        while(temp_stack.size()!=0)
        {
         //...
        }
     }
     //...

}

Simple as that..

[muran_pling]

I've told you you had missing parentheses, I told you to look for operator precedence and I've even highlighted the two faulty lines.. ' ! '

yeah i wrote those messages before i saw your hints... thanks man