Implement String.prototype.toLowerCase()

Question

Implement String.prototype.toLowerCase()

Description

The toLowerCase method returns the value of the string converted to lowercase. toLowerCase does not affect the value of the string itself.

Conditions Let count chars inside function and ignore all bootstrap code:

String.prototype.toLowerCase = function(){
  // code that count here
}

Other languages are welcome but JavaScript implemantation is target of this question. Let's just focus on ASCII charachters .

Example input and output:

"sOmeText".toLowerCase(); => "sometext"

Example implementation:

String.prototype.toLowerCase = function(){
  return this.split('').map(function(c){
     var cc = c.charCodeAt(0);
     if (cc > 64 && cc < 91) {
        return String.fromCharCode(cc + 32);
     }
     return c;
  }).join('');
}

Answer 1

Javascript 70 68

Building from @grc's answer:

for(s=i='';c=this[i++];s+=(parseInt(c,36)||c).toString(36));return s

Convert character to integer then back (works since Number.toString(36) will always be lowercase)

Test case: http://jsfiddle.net/Vh2TW/2/

input:

console.log('ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890~`-=_+{}[]:;\\\'\"<>,.?/!@#$%^&*()abcdefghijklmnopqrstuvwxyz'.toLowerCase())

output:

abcdefghijklmnopqrstuvwxyz1234567890~`-=_+{}[]:;\'"<>,.?/!@#$%^&*()abcdefghijklmnopqrstuvwxyz 

Update: -2 characters, thanks @copy

Answer 2

Bash, 10

Doesn't interface with javascript very well, but it works for everyday purposes.

tr A-Z a-z

Also, it's shorter than golfscript. (Booyah!)

---

Example Input:

echo "Hello World, asDFghJkL0123" | tr A-Z a-z

Output:

hello world, asdfghjkl0123

Answer 3

Golfscript, 17

{..64>\91<*32*|}%

Answer 4

J, 25

toLowerCase =: u:@(+32*91&>*64&<)@(3&u:)

Converting to numbers (3&u:) and back u: is quite uneasy.

Answer 5

Javascript, 86

String.prototype.toLowerCase = function () {
    s="";for(i=0;c=this.charCodeAt(i++);s+=String.fromCharCode(c>64&c<91?c+32:c));return s
};

Answer 6

Python (45)

l=lambda x:''.join(chr(ord(i)+('@'<i<'[')*32)for i in x)

Pseudocode:

l=func(x) {
  return toString( iterate(i in x) { chr(ord(i) + IsUppercase(i) * 32) } )
}

Explanation:
('@'<i<'[')*32): IsUppercase. '@' - 64, 'A' - 65, 'Z' - 90, '[' - 91: If 64<ord(i)<91, then return True and multiply it by 32 (to get 32).

Answer 7

VBA - 77 82

Function l(s)
'Counting only the stuff between Function and End
For x=1 To Len(s):m=Mid(s,x,1):l=l & IIf(m Like"[A-Z]",Chr(Asc(m)+32),m):Next
End Function

Answer 8

Ruby: 32 characters

s.gsub(/[A-Z]/){($&.ord+32).chr}

Sample run:
(In 35 characters it can be made a method of String class, to work just as the JavaScript sample.)

irb(main):001:0> class String
irb(main):002:1>   def toLowerCase  
irb(main):003:2>     self.gsub(/[A-Z]/){($&.ord+32).chr}
irb(main):004:2>   end
irb(main):005:1> end
=> nil
irb(main):006:0> "sOmeText".toLowerCase      
=> "sometext"

Answer 9

javascript 76 chars:

replace(/[A-Z]/g,function(b){return String.fromCharCode(b.charCodeAt()+32)})

Here's the full function:

String.prototype.toLowerCase = function () {
    return this.replace(/[A-Z]/g, function(b){
        return String.fromCharCode(b.charCodeAt()+32)
    });
}

Answer 10

Julia, 49 chars

L(s)=ascii([s[i]+32(64<s[i]<91)for i=1:endof(s)])

for all chars s[i] if 64 < s[i] < 91 is true, add 32 to the ASCII character point (32*true=32). If it’s false, then (32*false=0), and nothing is changed.

example:

julia> str
"ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#abcdefghijklmnopqrstuvwxyz~"

julia> L(str)
"abcdefghijklmnopqrstuvwxyz1234567890!@#abcdefghijklmnopqrstuvwxyz~"

The default method in Julia is lowercase(str)

julia> lowercase(str)
"abcdefghijklmnopqrstuvwxyz1234567890!@#abcdefghijklmnopqrstuvwxyz~"

the difference in timing and memory allocation:

julia> @time L(str)
elapsed time: 1.0263e-5 seconds (792 bytes allocated)

julia> @time lowercase(str)
elapsed time: 6.693e-6 seconds (224 bytes allocated)