Substituting a space for underscore in a character string

[#1]

Hi:

I have a long description of a product that includes a bunch of underscores __ which I don't want. I'd like to replace them with spaces instead. 

I've tried using substr(substitute(columnname, "_",""),1, 999) but that just makes the entire field blank. 
I've also tried the reverse (substitute(substr....) same problem.

Help!

JMP 17 FWIW. 

[#2 · Accepted solution]

Just using Substitute should be enough (or Substitute Into() depending on what you are doing)

Names Default To Here(1);

str = "aaa________b_c_________________d";
new_str = Substitute(str, "_", " "); // "aaa        b c                 d"

[#3]

Hi, notice that Jarmo's code replaces the underscores with a space character, " ", while your code replaced the underscores with the empty string, "", which was at least part of the problem.