# A little problem

**URL:** <https://www.ruby-forum.com/t/a-little-problem/192745>\
**Category:** Ruby\
**Created:** [August 4, 2010, 9:57pm UTC](https://www.ruby-forum.com/t/a-little-problem/192745 "2010-08-04T21:57:06Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![amiref](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/41988e/32.png) [@amiref](https://www.ruby-forum.com/u/amiref)\
**Post date:** [August 4, 2010, 9:57pm UTC](https://www.ruby-forum.com/t/a-little-problem/192745/1 "2010-08-04T21:57:06Z")

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Hi  
What is difference between these 2 codes ?  
(when I executed these codes result was the same )

* * *

def welcome1( name )  
puts “Hello#{name}”  
end

def welcome2( name )  
puts “Hello”+name  
end

welcome1( Amir )  
welcome2( Amir )

* * *

---

<div class="post-metadata">

**Author:** ![amiref](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/41988e/32.png) [@amiref](https://www.ruby-forum.com/u/amiref)\
**Post date:** [August 4, 2010, 10:12pm UTC](https://www.ruby-forum.com/t/a-little-problem/192745/2 "2010-08-04T22:12:55Z")

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In the first function, you’re performing interpolation on the variable;  
i.e. the #{} construct, when included inside “”, indicates to the  
interpreter to evaluate it as code, not text.

In the second function, you’re performing concatenation of the string  
“Hello” with the value of the variable name. In this case, the  
interpolation is automatic since the variable is outside the “”.

Hope this helps.

---

<div class="post-metadata">

**Author:** ![amiref](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/41988e/32.png) [@amiref](https://www.ruby-forum.com/u/amiref)\
**Post date:** [August 4, 2010, 10:16pm UTC](https://www.ruby-forum.com/t/a-little-problem/192745/3 "2010-08-04T22:16:26Z")

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Am 04.08.2010 21:57, schrieb Amir E.:

> puts “Hello”+name  
> end
> 
> welcome1( Amir )  
> welcome2( Amir )
> 
> * * *

Try this:

welcome1(3)  
welcome2(3)

You’ll see the difference. It’s because a string interpolation as in  
your first example implicitly calls #to\_s on it’s result.

Vale,  
Marvin  
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<div class="post-metadata">

**Author:** ![amiref](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/41988e/32.png) [@amiref](https://www.ruby-forum.com/u/amiref)\
**Post date:** [August 4, 2010, 10:18pm UTC](https://www.ruby-forum.com/t/a-little-problem/192745/4 "2010-08-04T22:18:12Z")

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Amir E. wrote:

> puts “Hello”+name  
> end
> 
> welcome1( Amir )  
> welcome2( Amir )
> 
> * * *

The first calls #to\_s and the second calls #to\_str. The #to\_str method  
is usually only defined for objects that are already String-like. The  
#to\_s is usually defined for everything.

def welcome1( name )  
puts “Hello#{name}”  
end

def welcome2( name )  
puts “Hello”+name  
end

Amir = Object.new

def Amir.to\_s  
puts “to\_s”  
“Amir”  
end

def Amir.to\_str  
puts “to\_str”  
“Amir”  
end

welcome1( Amir )  
welcome2( Amir )