What is the Spaceship Operator in PHP 7

Question

PHP 7  which will come out in November this year will introduce the Spaceship   lt     operator  What is it and how does it work   This question already has an answer in our general reference question about PHP operators

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Its a new operator for combined comparison. Similar to strcmp() or version_compare() in behavior, but it can be used on all generic PHP values with the same semantics as <, <=, ==, >=, >. It returns 0 if both operands are equal, 1 if the left is greater, and -1 if the right is greater. It uses exactly the same comparison rules as used by our existing comparison operators: <, <=, ==, >= and >.

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According to the RFC that introduced the operator   a  lt   gt   b evaluates to    0 if  a     b -1 if  a  lt   b 1 if  a  gt   b   which seems to be the case in practice in every scenario I ve tried  although strictly the official docs only offer the slightly weaker guarantee that  a  lt   gt   b will return      an integer less than  equal to  or greater than zero when  a is respectively less than  equal to  or greater than  b   Regardless  why would you want such an operator  Again  the RFC addresses this - it s pretty much entirely to make it more convenient to write comparison functions for usort  and the similar uasort and uksort    usort takes an array to sort as its first argument  and a user-defined comparison function as its second argument  It uses that comparison function to determine which of a pair of elements from the array is greater  The comparison function needs to return      an integer less than  equal to  or greater than zero if the first argument is considered to be respectively less than  equal to  or greater than the second    The spaceship operator makes this succinct and convenient    things                    foo    gt  5 5           bar    gt   abc                        foo    gt  7 7           bar    gt   xyz                        foo    gt  2 2           bar    gt   efg               Sort  things by  foo  property  ascending usort  things  function   a   b        return  a  foo    lt   gt   b  foo            Sort  things by  bar  property  descending usort  things  function   a   b        return  b  bar    lt   gt   a  bar          More examples of comparison functions written using the spaceship operator can be found in the Usefulness section of the RFC

User · Answer

The  lt   gt    Spaceship   operator will offer combined comparison in that it will    Return 0 if values on either side are equal Return 1 if the value on the left is greater Return -1 if the value on the right is greater   The rules used by the combined comparison operator are the same as the currently used comparison operators by PHP viz   lt    lt         gt   and  gt   Those who are from Perl or Ruby programming background may already be familiar with this new operator proposed for PHP7         Comparing Integers      echo 1  lt   gt  1    output  0     echo 3  lt   gt  4    output -1     echo 4  lt   gt  3    output  1        String Comparison      echo  x   lt   gt   x     output  0     echo  x   lt   gt   y     output -1     echo  y   lt   gt   x     output  1

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