Return variable with the highest value?

I have 3 variables: $num1, $num2, and $num3. Each represent the number of rows a table column has.

I want to find which variable has the highest variable, so I can use it in a for loop (shown below)

for ( $row = 1; $row <= $HIGHEST_VARIABLE; $row++) {
     ...
}

This probably was already answered, but I can't find it based on my sear开发者_如何转开发ches

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$highest = max($num1, $num2, $num3);