In Ruby, the '!' is known as the "bang". It performs an operation and changes the value of the variable in place, instead of creating a new variable with the changes.
Selecting even numbers from the `num` variable WITHOUT the '!' operator:
num = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] even = num.select(&:even?) puts 'num:' + num.to_s puts 'even:' + even.to_s output: num:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10] even:[2, 4, 6, 8, 10]
Without '!', it doesn't change the `num` variable; instead, it returns the modified value that we can store in a new variable.
Selecting even numbers from the `num` variable WITH the '!' operator:
Selecting even numbers from the `num` variable WITH the '!' operator:
num = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
even = num.select!(&:even?)
puts 'num:' + num.to_s
puts 'even:' + even.to_s
output:
num:[2, 4, 6, 8, 10]
even:[2, 4, 6, 8, 10]The '!' modifies the original array `num` in place.
Thus, the bang operator (!) is also known as a "destructive" operation because it modifies the variable, which might be used elsewhere in the code.
The bang operator also has another important use in Rails: handling exceptions. Let's keep it for the another post! Explanation on select, &:, to_s, also for another post.
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Bonus:
The bang operator also has another important use in Rails: handling exceptions. Let's keep it for the another post! Explanation on select, &:, to_s, also for another post.
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Bonus:
Guess what will happen in following example:
num = [2, 4, 6, 8, 10] even = num.select!(&:even?) puts 'num:' + num.to_s puts 'even:' + even.to_s
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output: num:[2, 4, 6, 8, 10] even:
The '!' returns nil if no changes were made.
Written by,
Written by,
Rushi Patel