Thread: While statement doesnt work if adding in line within

The function below has always worked for me until I tried to add in a counter on line 14. As soon as I add in this counter, the while loop is completely neglected. Also mysteriously if I add in line 14 while initialising c to some random value it works again. These seemingly unrelated changes in code make the while loop not execute while the other change makes it work again. Can anyone explain?

Code:

struct masternode* foo(ifstream* inputfile) {
    string word;
    int i = 0;
    char c; //defining c to some initialised value makes it work again after adding in line 14.
    struct masternode* root = NULL;
    while (c!=EOF){
        if((c = (*inputfile).get()) != ' ' && c != ':' && c!= ';' && c!='\n')
        {word += c; cout<<"aaa";}
        else {
            root = insert(root, word);
            word.clear();
            cout << "aaaa";
        }
        //i++; 
    }
    return root;
}

Well when you don't initialize c you have undefined behavior when you check it for EOF on line 6. Always initialize your variables before you try to use them in a calculation.

Jim

Originally Posted by jimblumberg

Well when you don't initialize c you have undefined behavior when you check it for EOF on line 6. Always initialize your variables before you try to use them in a calculation.

Jim

I thought that too. But how come if I keep line 14 out AND keep c uninitialized, it works flawlessly each and every time?
Or lemme guess, that's one of the mysterious outcomes of undefined behavior? ;-)

Originally Posted by Vespasian

Or lemme guess, that's one of the mysterious outcomes of undefined behavior? ;-)

Yep. Undefined == anything may happen, including that your program may actually work (some of the time).