delphi中如何实现类似SQL中字符左右补齐的功能？

Question

delphi中如何实现类似SQL中字符左右补齐的功能？例如要求STR1的长度为5，但实际只有3能否实现用某个字符（空格或0）来补齐其长度：'00str1'

Answer 1

给你三个小函数,自己很早写的，一直用着，没有优化，分别是在右边补，在左边补，在两边补。参数说明 ：instring  是你原来的字符串，如STR1
          numchars  是你想要的最终长度，如5
          fmtstr    是你想要填充的字符,如0                   自己试试吧。
function padr(instring:string;numchars:byte;fmtstr:char):string;
begin
  if numchars<=length(trim(instring)) then
     begin
       result:=copy(trim(instring),1,numchars);
     end
  else
    begin
       result:=trim(instring)+stringofchar(fmtstr,numchars-length(trim(instring)));
    end;
end;function padl(instring:string;numchars:byte;fmtstr:char):string;
begin
  if numchars<=length(trim(instring)) then
     begin
       result:=copy(trim(instring),1,numchars);
     end
  else
    begin
       result:=stringofchar(fmtstr,numchars-length(trim(instring)))+trim(instring);
    end;
end;function padc(instring:string;numchars:byte;fmtstr:char):string;
begin
  if numchars<=length(trim(instring)) then
     begin
       result:=copy(trim(instring),1,numchars);
     end
  else
    if  odd(numchars-length(trim(instring))) then
      begin
       result:=stringofchar(fmtstr,((numchars-1-length(trim(instring))) div 2))+trim(instring)+stringofchar(fmtstr,((numchars+1-length(trim(instring))) div 2));
      end
    else
      begin
       result:=stringofchar(fmtstr,((numchars-length(trim(instring))) div 2))+trim(instring)+stringofchar(fmtstr,((numchars-length(trim(instring))) div 2));
      end;end;