Curing bracketitus

Comments and questions to John Rowe.

Experience shows that some students have a habit of putting brackets everywhere, even when they are not needed:

a = (b) + (c*d);       // Don't do this
x = (y) + (2 * (y*z)); // or this

presumably because they aren't quite sure whether they need brackets or not.

This is a bad idea because:

1. The extra brackets are confusing
2. It makes the markers think you do not understand either C or basic arithmetic

Mathematical precedence

The "mathematical" operators * / % + - have exactly the same effect as in ordinary maths, with % being treated on the same basis as * and /, that is to say:

1. * / % bind more closely that + and -:

    
   2 * 3 + 1 => 7 not 4
   2 + 5 % 3 => 4 not 1
   

2. Operators with the same precedence are evaluated from left to right:

    
   12 / 3 * 2   => 8 not 2
   

No implicit multiplication

In maths we often use implicit multiplication with single-character variable names:

s = ut + 0.5at2

expands to:

s = u*t + 0.5*a*t*t

Once we understand the implicit multiplication convention we see that C's treatment of */+- is exactly the same as we have been used to.

Now try the quiz.