Why does Ruby's String#to_i sometimes return 0 when the string contains a number?
-
14-04-2021 - |
Question
I was just trying out Ruby and I came across String#to_i
. Suppose I have this code:
var1 = '6 sldasdhkjas'
var2 = 'aljdfldjlfjldsfjl 6'
Why does puts var1.to_i
output 6
when puts var2.to_i
gives 0
?
Solution
The to_i
method returns the number that is formed by all parseable digits at the start of a string. Your first string starts with a with digit so to_i
returns that, the second string doesn't start with a digit so 0 is returned. BTW, whitespace is ignored, so " 123abc".to_i
returns 123.
OTHER TIPS
From the documentation for String#to_i
:
Returns the result of interpreting leading characters in str as an integer
More exhaustive examples of to_i
:
irb(main):013:0* "a".to_i
=> 0
irb(main):014:0> "".to_i
=> 0
irb(main):015:0> nil.to_i
=> 0
irb(main):016:0> "2014".to_i
=> 2014
irb(main):017:0> "abc2014".to_i
=> 0
irb(main):018:0> "2014abc".to_i
=> 2014
irb(main):019:0> " 2014abc".to_i
=> 2014
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