How to replace blank value with space in abap

Hi Team,

i need to populate space if filed value is blank.

im reading data from itab to file, few fields of itab contain blank value ,

CONCATENATE: <gfs_data>-znachn
<gfs_data>-zmidnm
<gfs_dara>-zvorna
<gfs_data>-zbnksa

gfs_data>-zstat

<gfs_data>-zstrt1
<gfs_data>-zstrt2
<gfs_data>-zcity
<gfs_data>-zstate

<gfs_data>-zworloc INTO gs_output SEPARATED BY gc_sep1.

so my output file created in application server as below.

devediano~~Ckrole~70002348~~Outvendor RN CAP 1~~3107580~~~~11170000~0010.

now how do i insert space between ~~ ?

so my output file should be as beow.

devediano~ ~Ckrole~70002348~ ~Outvendor RN CAP 1~~3107580~ ~ ~ ~11170000~0010.

Thank you

NK