How to replace spaces inside a selection

Question

I have this text :

He's a self made man who gets what he wants.

The small blue forget me not flower was first used by the Grand Lodge.

And this function:

function MyFunction()
let myList1 = ["self made man", "gorget me not"]
for elem in MyList1
        if search("=/elem", 'W') == 0
           echo "I want to replace space by hyphen between this three words"  
           ---> CODE
        endif
endfor
endfunction

I want to get this text after executing the function :

He's a self-made-man who gets what he wants.

The small blue forget-me-not flower was first used by the Grand Lodge.

Can you help me to write the missing line (---> CODE) ?

Answer 1

You're looking for the substitute() function...

substitute({expr}, {pat}, {sub}, {flags})

• expr is the string to work on
• pat is the pattern similar to :s/pat/sub/g.
• sub is the substitution similar to sub in the same :s command.
• flags, should include "g" as in global (again, like :s)

So...

let elem = substitute(elem, ' ', '-', 'g')

The second param could also be '\s' indicating a single whitespace char.

Answer 2

Here's my function (based on @BLayer’s answer:

He's a self made man who gets what he wants. The small blue forget me not flower was first used by the Grand Lodge.

function MyFunction()
     let myList1 = ["self made man", "forget me not"]
     for elem1 in myList1
        if search("=/elem1", 'W') == 0
           let elem2 = substitute(elem1, ' ', '-', 'g')
           exe '%s/'elem1.'/'elem2
        endif
     endfor
endfunction

He's a self-made-man who gets what he wants. The small blue forget-me-not flower was first used by the Grand Lodge.