Ending loop

[fivestar]

When i enter an empty string, the program ends the way it should but it has a weird that comes up and im not sure whats wrong with it.
the message is, (terminate called after throwing an instance of 'std::out_of_range'
what(): basic_string::substr).

   #include <iostream>
   #include <string>
  
   using namespace std;
   
   int main(){
  
       string message, pig_message;
	   string::size_type pos;
      bool on;
	do{
        
    cout << "\nEnter the sentence"<<endl;
    getline(cin, message);
    if (message[message.size()-1] != ' ')
    {
        message += ' ';
    }
	while (!(message.length()<1)) {
        pos = message.find(" ");
        string word = message.substr(0,pos);
        message.erase(0,pos+1);

		
        if (word[0] == 'a' || word[0] == 'e' || word[0] == 'i' ||
			word[0] == 'o' || word[0] == 'u') {
			pig_message = word + "yay";
			cout << pig_message + " ";

		}
		else {
			pig_message = word.substr(1) + word[0] + "ay";
			cout << pig_message + " ";
        }
    }
            
	
  
    
    

 if (message==" "){
                on=false;
            }
    
}while(on=true);
return 0;
}

[coder777]

What is the string you enter when the out of range exception happens?

[fivestar]

I enter nothing I just hit enter. I thought that's equal to " ".

[coder777]

I thought that's equal to " ".

No, it is an empty string. Hence on line 15 message.size()-1 will be -1.

What happens on line 22 if line 20 message.find(" "); fails?

[Handy Andy]

Hello fivestar,

If your idea is to enter a blank line to quit you will need to move lines 42 - 44 to line 15 and make it look more like this:

if (message.length() == 0)
{
	on = false;
	continue;
}

To end the loop you need to deal with it just after the input i.e., the "getline". The "continue" will cause a jump to end of the do while loop to check the condition causing the loop to end. Next you will have to change line 46 from while(on = true); to while(on == true);. As it is you assign true to "on" thus making it true and an endless loop. I thing what you meant to do is while (on == true);. This is the equality operator checking to see if "on" is equal to true.

Hope that helps,

Andy

P.S. be sure to initialize "on" before you use it.

[fivestar]

Ok thanks