How to avoid 'break' in your while loop logic (Beginner)

avoid-break.cpp

// A
// [get some input from the user and store it in string str]
bool zFound = false;
while(str != "done")
{
    if(str.startsWith("Z"))
    {
        cout << "Z encountered! Terminating!" << endl;
        break;
    }
    
    doSomething();
    doSomethingElse();
    
    // get next input from user
}

// B: How is this different from example A?
while(str != "done" && !str.startsWith("Z"))
{   
    doSomething();
    doSomethingElse();

     // get next input from user
}

// C: Same functionality as A without using a break
while(str != "done" && zFound==false) // what is zFound?
{   
    doSomething();
    doSomethingElse();
     
    if(str.startsWith("Z"))
    {   zFound = true;
        cout << "Z encountered! Terminating!" << endl;
        
        // change some variable which will trigger the end of the loop
        
    }

     // get next input from user
}

if(zFound)
{
    count << "Ended with a Z!" << endl;
}