Reg BDC Upload prog

Hi Experts,

I have one issue in my BDC program, this prog is upload Journal entry. my Journal entry file name is like "378040". its number. its a cost center. now client requirement is different they want in front of the file added four zeros(0000). so now my file name is 0000378040. so how can i added 0000 in front of the file????

Can u give me suggetion.

Vishal.