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来源：蜘蛛抓取(WebSpider) 时间：2011-10-10 00:35 标签： which one is
ruby - What is the difference between print and puts? - Stack Overflow
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For example in this line of code I wrote, print and puts produce different results.
1.upto(1000).each { |i| print i if i % 2 == 0 }
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puts adds a newline to the end of the output. print does not.
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A big difference is if you are displaying arrays.
Especially ones with NIL.
For example:
print [nil, 1, 2]
[nil, 1, 2]
puts [nil, 1, 2]
Note, no appearing nil item (just a blank line) and each item on a different line.
print outputs each argument, followed by $,, to $stdout, followed by $\. It is equivalent to args.join($,) + $\
puts sets both $, and $\ to "\n" and then does the same thing as print. The key difference being that each argument is a new line with puts.
You can require 'english' to access those global variables with .
give some good hints:
print() → nil
print(obj, ...) → nil
Writes the given object(s) to ios. The stream must be opened for writing. If the output field separator ($,) is not nil, it will be inserted between each object. If the output record separator ($\) is not nil, it will be appended to the output. If no arguments are given, prints $_. Objects that aren’t strings will be converted by calling their to_s method. With no argument, prints the contents of the variable $_. Returns nil.
puts(obj, ...) → nil
Writes the given objects to ios as with IO#print. Writes a record separator (typically a newline) after any that do not already end with a newline sequence. If called with an array argument, writes each element on a new line. If called without arguments, outputs a single record separator.
Experimenting a little with the points given above, the differences seem to be:
Called with multiple arguments, print separates them by the 'output field separator' $, (which defaults to nothing) while puts separates them by newlines. puts also puts a newline after the final argument, while print does not.
2.1.3 :001 > print 'hello', 'world'
helloworld => nil
2.1.3 :002 > puts 'hello', 'world'
2.1.3 :003 > $, = 'fanodd'
=> "fanodd"
2.1.3 :004 > print 'hello', 'world'
hellofanoddworld => nil
2.1.3 :005 > puts 'hello', 'world'
puts automatically unpacks arrays, while print does not:
2.1.3 :001 > print [1, [2, 3]], [4]
[1, [2, 3]][4] => nil
2.1.3 :002 > puts [1, [2, 3]], [4]
print with no arguments prints $_ (the last thing read by ), while puts prints a newline:
2.1.3 :001 > gets
hello world
=> "hello world\n"
2.1.3 :002 > puts
2.1.3 :003 > print
hello world
print writes the output record separator $\ after whatever it prints, while puts ignores this variable:
mark@lunchbox:~$ irb
2.1.3 :001 > $\ = 'MOOOOOOO!'
=> "MOOOOOOO!"
2.1.3 :002 > puts "Oink! Baa! Cluck! "
Oink! Baa! Cluck!
2.1.3 :003 > print "Oink! Baa! Cluck! "
Oink! Baa! Cluck! MOOOOOOO! => nil
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puts call the to_s of each argument and adds a new line to each string, if it does not end with new line.
print just output each argument by calling their to_s.
for example:
puts "one two":
{new line}
puts "one two\n":
{new line} #puts will not add a new line to the result, since the string ends with a new line
print "one two":
print "one two\n":
{new line}
And there is another way to output: p
For each object, directly writes obj.inspect followed by a newline to the program’s standard output.
It is helpful to output debugging message.
p "aa\n\t": aa\n\t
The print command just takes whatever you give it and prints it to the screen. puts (for "put string") is slightly different: it adds a new (blank) line after the thing you want it to print.
if you would like to output array within string using "puts", you will get the same result as if you were using "print":
puts "#{[0, 1, nil]}":
[0, 1, nil]
But if not withing a quoted string then yes. The only difference is between new line when we use "puts" .
If you use 'print' it will not create a new line automatically.
With 'puts' it does create a new line automatically.
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