C++ - formula in a while loop

[zelmila19]

How do i write the formula for calculating the total sales and average for this program:

[code=cpp]
while (sales !=-1)
{
i <= 12; i++;
cout << fixed << setprecision(2) << "Please enter your sales for month " << i << ": ";
cin >> sales;
} //end while

i <= 12; i--;
cout << "For " << i++ << " months: ";

cout << fixed << setprecision(2) << "Total sales: $ " << totalSales << endl;
cout << fixed << setprecision (2) << "Average sales: $ " << average << endl;

[/code]

Can someone help me if I'm doing the right thing here because it is giving some kind of warning but dont know why. Please help!

[scruggsy]

using namespace std;
using std::fixed;
using std::setprecision;

No big deal, but the second two using directives are unnecessary here.

	i <= 12; i--;

What are these two statements meant to accomplish? Are you trying to implement a for loop?

Beyond that, post the text of the warning you're getting.

[weaknessforcats]

Generally, you cannot use operators like ==, !=, >, <, <=, >=, etc wth floating point numbers.
Due to the automatic rounding, these operators may report a condition as true when the numbers
are only close in value.

Google for Floating Point Arithmetic or read IEEE 754 standard specification for details.

To compare two floating point numbers, you have to establish a sigma error tolerance.

if (fabs(i - j) < 0.000001) { ... // almost equal }

[zelmila19]

using namespace std;
using std::fixed;
using std::setprecision;

No big deal, but the second two using directives are unnecessary here.

	i <= 12; i--;

What are these two statements meant to accomplish? Are you trying to implement a for loop?

Beyond that, post the text of the warning you're getting.

No am not trying to implement a for loop I just want to use a while loop but I want the months to automatically just come as Month1...Month2 ...etc.
The program is giving me this warning:

warning C4552: '<=' : operator has no effect; expected operator with side-effect

[weaknessforcats]

i <= 12 will be either true or false. That is, this will evaluate to 0 or 1. Plus the 0 or 1 is not used so the whole statement is pointless. That's the essence of the compiler warning.

[zelmila19]

i <= 12 will be either true or false. That is, this will evaluate to 0 or 1. Plus the 0 or 1 is not used so the whole statement is pointless. That's the essence of the compiler warning.

Thanks guys but i still cant get the expected results cos I do not know how to code the calculations for the total sales and average sales.......cou ld someone give me an idea on how to do that???

[weaknessforcats]

For starters, you have one sales variable. If you want sales by month I would expect you would need 12 sales variables. Maybe in an array. That way the 5th variable could be May.

All you have to do is display the variables. Add them up and divide by 12 and you have average monthly sales. etc...