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In a book I am currently reading, there is this excerpt: You can also use a floating-point value as a loop counter. Here's an example of a for loop with this kind of counter: double a(0.3), b(2.5); for(double x = 0.0; x <= 2.0; x += 0.25) cout << "\n\tx = " << x << "\ta*x + b = " << a*x + b; This code fragment calculates the value of a*x+b for values of x from 0.0 to 2.0 , in steps of 0.25 ; however, you need to take care when using a floating-point counter in a loop. Many decimal values cannot be represented exactly in binary floating-point form, so discrepancies can build up with cumulative values. This means that you should not code a for loop such that ending the loop depends on a floating-point loop counter reaching a precise value. For example, the following poorly-designed loop never ends: for(double x = 0.0 ; x != 1.0 ; x += 0.2) cout << x; The intention with this loop is to output the value of x as it varies from 0.0 to 1.0 ; however, 0.2 has no exact representation as a binary floating-point value, so the value of x is never exactly 1 . Thus, the second loop control expression is always false, and the loop continues indefinitely. Can someone please explain how the first code block runs while the second doesn't?

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