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Can you change value of a substring?

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  Can you change value of a substring? jonas.thornvall@gmail.com - 2014-06-18 12:39 -0700
    Re: Can you change value of a substring? jonas.thornvall@gmail.com - 2014-06-18 13:09 -0700
      Re: Can you change value of a substring? Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-18 23:18 +0200
        Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-19 00:35 +0200
          Re: Can you change value of a substring? jonas.thornvall@gmail.com - 2014-06-18 15:52 -0700
      Re: Can you change value of a substring? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2014-06-18 16:14 -0700
    Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-18 22:10 +0200
      Re: Can you change value of a substring? jonas.thornvall@gmail.com - 2014-06-18 13:17 -0700
        Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-18 22:52 +0200
          Re: Can you change value of a substring? jonas.thornvall@gmail.com - 2014-06-18 14:03 -0700
            Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-19 00:07 +0200
              Re: Can you change value of a substring? jonas.thornvall@gmail.com - 2014-06-18 15:28 -0700
      Re: Can you change value of a substring? jonas.thornvall@gmail.com - 2014-06-18 13:20 -0700
        Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-18 23:22 +0200
          Re: Can you change value of a substring? jonas.thornvall@gmail.com - 2014-06-18 14:40 -0700
            Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-19 00:31 +0200
      Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-18 23:42 +0200
        Re: Can you change value of a substring? Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-19 00:13 +0200
          Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-19 00:45 +0200
            Re: Can you change value of a substring? Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-19 01:32 +0200
              Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-19 09:43 +0200
          Re: Can you change value of a substring? Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-19 01:48 +0200
            Re: Can you change value of a substring? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-19 09:56 +0200
    Re: Can you change value of a substring? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2014-06-18 16:12 -0700

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#24943

Christoph Michael Becker <cmbecker69@arcor.de> wrote on 19 jun 2014 in 
comp.lang.javascript:

> Thus I'd say numbers and strings are immutable, but arrays are not.

Not really, as the members of the arrays are just variables.

both

var b = 'qqq';

and

a[7] = 'rrr';

are likewize immutable. 

[I suspect that in applications, the array members are not even grouped 
together, but are handled the same as the simple variables.]

-- 
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

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#24935

Stefan Ram wrote:

> Christoph Michael Becker <cmbecker69@arcor.de> writes:

The attribution of the following is missing.

>>> An analog clock and a human usually have hands, 
>>> does that fact mean they have "something to do" with eachother? 
>> Thumbs up! :)
> 
>   In fact they have so many things in common: Both have a
>   mass, the mass is always between 1E-3 and 1E+3 kg, both
>   exist on the earth, but not on the asteroid Proserpina, both
>   have parts that are called »hands«, and and and. I can not
>   enlist all that which they have in common!
> 
>   Hint: »having something to do with« does not mean »to be the
>   same«.

Of course.  However, finding *any* relationship doesn't mean much...

>> Consider passing a string as argument to a function; if the function is
>> able to actually change the string, the programmer has to be aware of
> 
>   A function can never change a string in any programming
>   language, because a string is a value, just as a number.

I beg to differ.  Consider C:

    #include <stdlib.h>
    #include <assert.h>

    void doIt(char* string)
    {
        string[0]++;
    }

    int main()
    {
        char string[256] = "foo";
        assert(strcmp(string, "foo") == 0);
        doIt(string);
        assert(strcmp(string, "goo") == 0);
    }

-- 
Christoph M. Becker

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#24944

Christoph Michael Becker <cmbecker69@arcor.de> wrote on 19 jun 2014 in 
comp.lang.javascript:

>>   A function can never change a string in any programming
>>   language, because a string is a value, just as a number.

When you see a string as a named value, you can change that value,
if you don't mind it is stored somewhere else every time.

Only Javascript offers no direct method to do that, well,
discounting the string operator +=, the method concat(), etc.

Unnamed string values inside methods, like regex methods, 
could be handled and stored quite differently inside the engine.


> I beg to differ.  Consider C:

I too beg to differ.

Concider original Forth, 

where each string is stored as a length value plus the the allotted number 
of bytes or words.

You can find the memory address of say the third character and change that.

But that is all semantics depending on the definition of "string". 

-- 
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

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#24930

On Wednesday, June 18, 2014 2:39:21 PM UTC-5, jonas.t...@gmail.com wrote:
> Can i change value of a substring or do i have to read the string into an Array?
> 
> I want to change the value of substring a char in nstring. Is following possible?
> 
> nstring="12345"
> 
> n = nstring.length;
> 
> val=nstring.substring(n-1,n);
> 
> //Is it possible to subtract and add to the character in val?
>       val--;                  
> 
> //Can you force a value in a string or must i read into an array 
>       nstring.substring(n-1,n)=val;

In JavaScript, a String is an immutable value and not a collection. You don't necessarily have to convert it into an array though to operate on it.

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