Loop just doesn't want to stop looping when I tell it to...

anonymous91 · #1 27-Oct-2009, 18:54

Obviously the problem is me and not the loop.

But here's a watered down version of my code with the cout strings changed so there's no confusion.

CPP / C++ / C Code:

int main()
{
    int a;
    a=5;
    string x;
    
    for (;a=5;)
    {
          cout << "A yes or no answer is needed. Y/N:";
          cin >> x;
          cout << a;
          if (x=="y") { cout << "Your answer was Yes."; a=6;}
          else if (x=="n") { cout << "Your answer was No."; a=6;}
          else if (a=5) { cout << "Your answer was invalid.\n"; }
    }
    return 0;
}

also.....the second "else if" i tried "else" but then i get the error - " expected `;' before '{' token "

apparently the "int a" isn't changing its value to 6 when the if statement is being used.

say i enter "y" or "n", it will give me the respective cout, but then it will say "your answer is invalid" and keep looping.

LuciWiz · #2 27-Oct-2009, 18:56

Hint: In C/C++, you test for equality with the "==" operator; "=" represents assignment.

Best regards,
Lucian

Edit: If you copied some of the code from somewhere else, I recommend reading up on the structure of the for loop.

anonymous91 · #3 27-Oct-2009, 18:59

one more thing.

the "cout << a;" that i have there doesn't "cout" when i run the program.

and that's the only reason i put it there, to see if it worked or not.
which is what helped me determine it must be something with the value of "int a".

LuciWiz · #4 27-Oct-2009, 19:02

Did you input a value when "cin" asked for one, so the program flow could continue? If not, read up on what "cin" does.

Btw, I am going to sleep

anonymous91 · #5 27-Oct-2009, 19:07

Quote:

Originally Posted by LuciWiz

Hint: In C/C++, you test for equality with the "==" operator; "=" represents assignment.

Best regards,
Lucian

Edit: If you copied some of the code from somewhere else, I recommend reading up on the structure of the for loop.

okay so i edited this part.

CPP / C++ / C Code:

else if (a==5) { cout << "Your answer was invalid.\n"; }

and it still loops.

anonymous91 · #6 27-Oct-2009, 19:18

Quote:

Originally Posted by LuciWiz

Did you input a value when "cin" asked for one, so the program flow could continue? If not, read up on what "cin" does.

the line:

CPP / C++ / C Code:

cin >> x;

asks for an input and assigns the input that value.

the sentence says "A yes or no answer is needed. Y/N:"
and when i enter y or n, 'x' gets assigned "y" or "n".

which is then what i have the if and else statements for.
so depending on what value is given to 'x', the program will output a different sentence...and then re-assign 'a' to 6, so the loop stops looping.

it's only supposed to loop if 'x' was assigned something other then "y" or "n".

but it's looping regardless.

and not cout'ing 'a' when i ask it to.

thanks for the help, but im pretty sure the problem isn't the "cin >> x;" line.

TurboPT · #7 27-Oct-2009, 21:16

Although you changed a=5 to a==5 in the else if condition, the loop's condition has the same problem.
(unless you've fixed it since then, it would probably be a good idea to post your latest working code in your next post)

anonymous91 · #8 27-Oct-2009, 22:29

this is what i have so far:

CPP / C++ / C Code:

#include <iostream>
#include <string>
using namespace std;

int main()
{
    int a;
    a=5;
    string x;
    
    for (;a=5;)
    {
          cout << "A yes or no answer is needed. Y/N:";
          cin >> x;
          cout << a;
          if (x=="y") { cout << "Your answer was Yes."; a=6;}
          else if (x=="n") { cout << "Your answer was No."; a=6;}
          
          if (a==5) { cout << "Your answer was invalid.\n"; }
    }
    return 0;
}

Howard_L · #9 27-Oct-2009, 22:53

Your problem is caused by a mistake in the condition test in this statement:

CPP / C++ / C Code:

for (;a=5;)

Read up on condition testing and loops here: cplusplus.com/doc/tutorial/control.html

jnCPP · #10 28-Oct-2009, 00:51

I'm wondering why you're using a string for one character?
Also, you might run into errors because your (posted) code doesn't prepare for the possibility of a 'Y' or 'N'.
I suggest using toupper (if you're allowed to)
or alternatively using the || (or)

CPP / C++ / C Code:

if (x == 'Y' || x == 'y')
{code}
else if (x == 'N' || x == 'n')
{code}
else 
{code}

also, check as to why you want your loop to break after an invalid statement and not after 'no' or 'yes'.. unless you wanted the loop to stop after something other than no or yes was enterd.. but if that's the case you should state it.

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