Interpretation of for loop.

Question

for every j != i in {0,....,n-1}

How to interpret this for loop? I never seen this type of definition of for loop.

Is it like - j=0 to n-1; j !=i ; ++j

Answer 1

Here is the probable interpretation:

for every $j \neq i$ in $\{0,\ldots,n-1\}$:

  code

should be interpreted as:

for every $j$ in $\{0,\ldots,n-1\}$:

  if $j \neq i$:

    code

This is similar to the way this kind of statement is interpreted in mathematical text.

It is also possible that the roles of $i$ and $j$ should be switched — this should be clear from context, and it's an ambiguity that also exists in mathematical texts.

As mentioned in Evil's answer, if neither $i$ nor $j$ has been defined, then the interpretation is probably

for every $i,j$ in $\{0,\ldots,n-1\}$:

  if $i \neq j$:

    code

Answer 2

There is another interpretation, both $i, j$ might be variables, in that case it is double loop:

for every $j$ in $\{0,\ldots,n-1\}$:

  for every $i$ in $\{0,\ldots,n-1\}$:

    if $j \neq i$:

      code

Simply reading it out loud helps only if we know beforehand if $i$ is fixed variable or another counter, so there is context missing.

Answer 3

Just read it out loud. "For every $j$ that is not equal to $i$, in $\{0, \dots, n-1\}$."

In my opinion, it would be better to have written "For every $j\in\{0, \dots, n-1\}\setminus\{i\}$."