CODEWITHSUNDEEP
c++linked-list
WestonBuckeye
WestonBuckeye

Reputation: 45

Read from file, store into linked list then print to file again

I have a constructor and a destructor for a class called StringList. I created functions that add, remove and clear the strings within the linked list. I want this program to retain its added strings even when the program is ended. One way that i can do this is to have my constructor read from a file and my destructor save the strings to that same file. I am brand new into programming and ive been searching how to do this for a linked list but ive hit dead ends so far. The file i read from is called Read.txt, when the destructor is called, all the strings are saved to this file. The Read.txt file contains a list as such:

HELLO
MOM
BART
CART
PETS

Here is the code:

StringList::StringList()
{
    ifstream infile;
  // i know how to open the file i just dont really have a single clue on how to set each string into the linked list


}

StringList::~StringList()
{
    StringListNode *next;
    for (StringListNode *sp = pTop; sp != 0; sp = next)
    {
        next = sp->pNext;
        delete sp;
    }
}

Any suggestions or examples would be much appreciated. If you need further info or anymore code i wrote, please let me know asap

Upvotes: 0

Views: 2333

Answers (2)

Annie Kim
Annie Kim

Reputation: 905

Here is my suggestion. Hope that can help you.

StringListNode *cur = pTop;  // I guess pTop is the head of your list
for each string s  // read
{
    cur = new StringListNode(s);  // call the constructor of StringListNode
    cur = cur->pNext;
}

Upvotes: 3

pippin1289
pippin1289

Reputation: 4939

Here is some code to accomplish what you want. For reading, you should have a while loop over the input file stream until no more strings can be read. Add each string using your already written add function. Then for destruction you should open a file stream and save each element of the list accordingly.


StringList::StringList() {
    ifstream ifs("MyFilename.txt");
    string s;
    while(ifs >> s)
        Add(s);
}

StringList::~StringList() {
    ofstream ofs("MyFilename.txt");
    StringListNode *next;
    for (StringListNode *sp = pTop; sp != 0; sp = next)
    {
        ofs << sp->element << endl;
        next = sp->pNext;
        delete sp;
    }
}

Upvotes: 0

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