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Difference between puts and print for Array
I have an array
friends = Array.new
friends[0] = "Mad man"
friends[1] = "hey"
There's two ways to print it (using print or puts). At first I tried print
print friends
which gave:
["Mad man", "Hey"]
When I tried puts
puts friends
I got:
Mad man
Hey
I thought that the difference between puts and print is puts add a new line and, print doesn't. But, why was print directly giving output of that array (and not separating elements)?
1 answer
The official ruby documentation explains the observed difference between the outputs of print and puts. The important bits are as follows:
For any non-string object given as argument (such as an array, for example), print invokes the object's to_s method and outputs the resulting string returned by to_s. Quote from doc (link):
Each given object that isn't a string will be converted by calling its to_s method.
And as it so happens, the to_s method of your array produces the ["Mad man", "Hey"] output you observe (and which is also documented, link).
puts
On the other hand, puts behaves differently when provided with an array. Quote from doc (link):
If called with an array argument, writes each element on a new line. Each given object that isn't a string or array will be converted by calling its to_s method.
Contrary to print, puts does NOT call the array's to_s method but rather directly outputs the array elements line-by-line.
By the way, you can also achieve almost the same output as print with puts by explicitly invoking the to_s method like:
puts friends.to_s
which will output
["Mad man", "hey"]
(It is only almost the same output as print friends, since puts writes a newline at the end of the output, whereas print does not -- unless of course you change the output record separator to a newline. See also hkotsubo's comment below.)
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