C++ :: Possible To Change A Single Variable From A Pointer?
Dec 2, 2013
I am stuck at a problem where I have two pointers pointing to the same object, and I need to change an int on one of the pointers but point to the same object.
To be more specific, there is an array of Item objects. A long list of items a player can buy. Then, there is the player's inventory, a vector pointer. Whenever a player buys an item, it sets the pointer to the bought object.
The problem arises when he buys two of the same object. I tried to identify the objects with an ID, but it does nothing, because they are just pointing to the same object, and so I have no way of telling them apart.
This is further complicated by the fact that it is a polymorphic object. So, I can't simply make a new every time I buy an object, without making a hassle. Well, at least I am not familiar with that kind of code just yet.
For Example i have made a text file included some students data. Now i want to change just a single student data. That file should remain same just that student's data replace.
So, I've made programs like Prime number searchers and such. But the problem is if I use an int or long int variable for the program I am limited by the variable size. I can't search through numbers larger than their memory size. So my question is: Is there a way to allocate memory to a single variable, NOT AN ARRAY, so I can make a variable as many bytes as I want?
I'm making a system like twitter for class called ShoutOut.com I want to be able to get the PublicShoutOut pointer pointed to by the start iterator and assign it to firstShoutOutToDisplay and secondShoutOutToDisplay because I need that in order to pass the pointers to one of my functions. When I step through the debugger the values in start are all default values like "" and so are the values in this->firstShoutOutToDisplay but the message that start points to is being output just fine.
EDIT: got rid of irrelevant code. Am I using the correct syntax to do this?
if (start != finish) { //getting these because a shoutout needs to be passed to the function that displays //options for a shoutout this->firstShoutoutToDisplay = (*start);
I'm currently writing a poker game and am trying my best to avoid using global variables. I have a few variables in int main() which i was hoping to use to store the value of each players hand. I then created a function which calculates the value of the hand but cannot get this value back into the main function.
For example:
Code: #include <iostream> using namespace std; void getValue(int value) { value = 4;
[Code] ....
Is there any way i can get the value of value using this function? If not what can I do?
when i pass a string pointer to a function such as string *str = new string(""); and pass that string to a handleElement() function e.g. handleElement(str), and i change the value in the function it simply doesn't change when the function exits as though it's passing it by value or something, even though it gives the pointer address.. I've now changed the code to use double pointers and pass the reference of the str pointer and it works but it seems ugly to use double pointers for this.
//handles when a new element is encountered when parsing and adds it to the parse tree bool ParseBlock::handleElement(char cur, string *curString, int count, bool isOperator) { countNode = new ParseNode(count); //keep track of numbers and strings if they exist and insert them if(!curString->empty()){ if(isNumber(*curString)
I started to learn programming through this site two weeks or so ago. I've got a book with exercices and so on, and one of them involves calculating e within a tolerance given by the user.
The formula for calculating e is the summation of 1+(1/i!), where i -> n.
So, here's the code and I'll explain the problem below:
Code:
#include <stdio.h> int main() { float error; float terme; float sumatori = 0; int cicle_euler = 1; int factorial;
[Code]...
For some reason, when I set factorial to cicle_factorial, factorial remains 0, which I find puzzling; the program always halts when 1 + sumatori is 2.0 no matter what error is.
This must be a common problem and I suspect it has to do with some distinction between variables inside a loop and variables outside it, but as I lack technical vocabulary I can't seem to find anything on Google.
what happens to pointer pt when string s is reallocated to accommodate bigger size? does it updates itself or does it points to previous s which is not used anymore?
#include <iostream> #include <string> using namespace std; int main() { string s= "aa";
Suppose you a class declared with a pointer initialization variable. When writing the copy constructor, how would one make a deep copy of the pointer variable? Can it be done in the same manner as automatic variables i.e. in the initialization list or in some other manner?
I need to initialize a pointer variable with a knowing address. See code below, ptr is the final destination and value of ptr_address contains the address value, so I need to do something like ptr = *ptr_address.
Code:
int *ptr; int *ptr_address; int address; address = 0x10000005; ptr_address = &(address); ptr = *ptr_address;
The problem is that compiler gives the following warning message:
warning: assignment makes pointer from integer without a cast [enabled by default]
Is my code wrong or there is any other way to do it without receiving this compiler warning?
this question would their be a different process if they asked "declare and initialize a pointer to the variable int cost[N][N]" Here's what I have so far
[#include<stdio.h> int main() { int a; // Step 1 int *ptr; // Step 2 a = cost; // Step 3 ptr = &a; // Step 4 return(0);
I'm writing a delete function for a linked list, and I'm having issues with this bit of code:
void deleteNode(int data){ node* del = NULL; t = h; n = h; while(n != NULL && n->_data != data){ t = n; n = n->next; } }
Or more precisely, this portion:
&& n->_data != data
n is my new node variable, _data is the storage variable in the private section of my class, and data is the information being searched for that needs to be deleted. Everything works without this section of the code. My assumption is that n->_data is somehow wrong, but I don't see how. I've tried everything I can think of- using parenthesis, using the variable rather than the pointer, I've tried expressing the pointer in a different way, I've tried using my t variable rather than n, and I've found examples online that use this exact same expression without any issues.
I am making a function that will return a pointer to a long long variable. For example, I have the next variable prototype: Code: long long funcName(long long x, int s); I want to change the return value, and the first parameter to pointers to long long.
if possible i want avoid the '&' when i assign the variable address.(variant2 f=varname;//like you see i don't use the '&') for the moment i just need put the address to Variant pointer. but i receive several errors .
