REPLACE Doesn't.

[toml_12953]

I'm trying to replace spaces in a string with zeroes but I get the same string back unchanged. The program below prints
" 9"
" 9"
Of course I'm doing something wrong but I can't figure out what. REPLACE does work at the home screen.

Tom L

PHP Code:

EXPORT test()
BEGIN
  local x,i;
  print();
  x:="    9";
  print(""""+x+"""");
  for i from 1 to 4 do
   replace(x,i,"0");
  end;
  print(""""+x+""""); 
END; 


[Dieter]

(03-31-2017 01:40 PM)toml_12953 Wrote:  

PHP Code:

for i from 1 to 4 do
   replace(x,i,"0");
  end; 


This probably is a very dumb answer, as I do not even have a Prime at hand to check it. But in all programming languages I know the "replace" string function does not replace the i–th character, instead it replaces one substring by another. Like this:

replace("apple pie", "apple", "orange") => "orange pie"

So the right approach may be something like a simple replace(x," ","0"). No for-loop required.

But again: probably this is a very stupid answer. You should know since you've got the manual. ;-)

Dieter

Edit: replaced a 9 with a 0.

[eried]

You have to store the new result:

replace(x,i,"0");

change to:

x:=replace(x,i,"0");

[toml_12953]

(03-31-2017 01:48 PM)Dieter Wrote:  

(03-31-2017 01:40 PM)toml_12953 Wrote:  

PHP Code:

for i from 1 to 4 do
   replace(x,i,"0");
  end; 


This probably is a very dumb answer, as I do not even have a Prime at hand to check it. But in all programming languages I know the "replace" string function does not replace the i–th character, instead it replaces one substring by another. Like this:

replace("apple pie", "apple", "orange") => "orange pie"

So the right approach may be something like a simple replace(x," ","9"). No for-loop required.

But again: probably this is a very stupid answer. You should know since you've got the manual. ;-)

Dieter

I tried this:

PHP Code:

x:="apple pie";
replace(x, "apple", "orange");
print(x); 


"apple pie" prints. I'm really craving orange pie! It seems to be a problem replacing characters in a variable.


Tom L

[Han]

(03-31-2017 02:06 PM)toml_12953 Wrote:  I tried this:

PHP Code:

x:="apple pie";
replace(x, "apple", "orange");
print(x); 


"apple pie" prints. I'm really craving orange pie! It seems to be a problem replacing characters in a variable.


Tom L

See eried's post prior to yours; you need to save the result since the function does not modify the input in place.

[toml_12953]

(03-31-2017 02:10 PM)Han Wrote:  

(03-31-2017 02:06 PM)toml_12953 Wrote:  I tried this:

PHP Code:

x:="apple pie";
replace(x, "apple", "orange");
print(x); 


"apple pie" prints. I'm really craving orange pie! It seems to be a problem replacing characters in a variable.


Tom L

See eried's post prior to yours; you need to save the result since the function does not modify the input in place.

Ah! I didn't realize that even parameters in predefined functions are passed by value. Thanks!

Tom L

[Tim Wessman]

(03-31-2017 02:15 PM)toml_12953 Wrote:  Ah! I didn't realize that even parameters in predefined functions are passed by value. Thanks!

Everything in PPL is passed by value. I believe the only exception here is that when you cross into the CAS inside a program, variables are passed as variables so that the CAS can do what it needs with them.

[Dieter]

(03-31-2017 02:15 PM)toml_12953 Wrote:  Ah! I didn't realize that even parameters in predefined functions are passed by value.

Does this mean that this...

Code:

x:="apple pie";
x:=replace(x, "apple", "orange");
print(x);

...actually works on the Prime?
And what about your original example and x:=replace(x, " ", "0") then?

Dieter,
just curious. ;-)

[toml_12953]

(03-31-2017 05:25 PM)Dieter Wrote:  

(03-31-2017 02:15 PM)toml_12953 Wrote:  Ah! I didn't realize that even parameters in predefined functions are passed by value.

Does this mean that this...

Code:

x:="apple pie";
x:=replace(x, "apple", "orange");
print(x);

...actually works on the Prime?
And what about your original example and x:=replace(x, " ", "0") then?

Dieter,
just curious. ;-)

Yes! I can now have my orange pie. and I get 00009 with that replace.

Tom L