Are semicolon-terminated if-statements good coding practice?

Question

I am looping i, j, k and n. I want a statement to execute except when k == j and n == k.

If I use the code like this:

if (k != j && n != i)
      //statement

The statement will not execute in two cases:

1. When k != j when n == j.
2. When k == j when n != j. (which is not what I need)

So I used a code like this:

if (k == j && n == i)
    ;else
    //statement

By this code the statement will successfully execute except when k == j && n == i.

Is semicolon-terminated if-statements is a good way of coding in C++?

Answer 1

No it's not a good way of coding. The usual way is to use ! to invert the logic:

if(!(k==j && n==i))
    //statement

Or you could use De Morgan's Law to invert the logic:

if(k!=j || n!=i)
    //statement

Answer 2

Your problem is that you're negating the condition incorrectly. You should just do:

if (!(k==j && n==i))
  // statement

Or, by De Morgan's laws:

if (k != j || n != i)
  // statement

Answer 3

... is a good way of coding?

No.

You should write

if (!(k == j && n == 1))
{
    //statement
}

Putting a semicolon after an if, for, or while is almost always wrong. It is highly unexpected and makes reading your code very difficult.