Hey!! I am using IDL and want to store the values found using a loop. The only problem is each time the loop goes round, it re-writes all the values in the array. How do I store the values for use once the loop has finished? Seems like a really simple thing to want to do, Im surprised I can't do it or havn't had to do it before. Anyways here is what I have got so far, Ive had a go but it doesnt work: for num=0, 32 do begin DMID=(Basically I read the values in to this array from 32 seperate files) result=where(DMID, count) imin=-1 imax=0 for imin, imax do begin imax=imax+count DMIDs[imin:imax]=DMID imin=imin+count endfor endfor This doesnt work anyway and seems like a slightly mental way of going about it to me but its what a friend told me to do. Any help, most appreciated.