Preface: Of course, writing constants to the left or right of the == operator has no effect on the operation itself, they are just two different writing styles. So I’m sure a lot of people aren’t going to change their style just because they read some post that says “constants should be on the left side.” After all, it’s just a habit.
However, writing constants to the left of the operator may make it easier to check errors in some cases. Look at the following example:
Segment one, if and only if
flag == 5
Execute the contents of the loop body when:
int
flag;
.
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while (flag == 5)
{
/* do something */
}
Segment two, the hand nearly knocked out a =, will cause an infinite loop, because
flag = 5
Always true. It is not easy to debug an error like this when the code volume is large:
int
flag;
.
while (flag = 5)
{
/* do something */
}
In section 3, the constant is placed on the left, so it is safe to omit an = sign. The compiler will tell you that there is an Error:
int
flag;
.
while (5 = flag)
{
/* do something */
}
To sum it up in one sentence:
Good writing style allows bugs to show up at compile time rather than run time.