I'm not sure what you mean, but this might be on the right track.

# and syntax
if (($i > 0) && ($i < 40)) {
    # do something
}

# or syntax
if (($i >0) || ($i < 40)) {
    # do something
}
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You can of course also use the actually words 'and' and 'or', but I believe they have different precedence compared to the symbol forms.

Update: The symbol form of 'or' (||) has higher precedence than the word form.