谁能给个好用的四舍五入函数？

Question

自带的round 好像跟我们平常说 四舍不入不太一样 比如round(10.5)=10
上网找了一个 但识别不出来 10.45＝5这样的功能。

Answer 1

function RoundClassic(R: Real): Int64;
begin
Result:= Trunc(R);
if Frac(R) >= 0.5 then
    Result:= Result + 1;
end;

Answer 2

10.45 -> 10
10.50 -> 11
8.49 -> 8
9.96 -> 10
12.58 -> 13
试了一下，应该没问题

Answer 3

uses Math;function MyRound(Value: Extended; RoundMode: TFPURoundingMode = rmUp): Int64;
var
  RM: TFPURoundingMode;
begin
  RM := GetRoundMode;
  try
    SetRoundMode(RoundMode);
    Result := Round(Value);
  finally
    SetRoundMode(RM);
  end;
end;例：myRound(10.45)->10.5

Answer 4

wzwcn  这个方法可行！ 
 

Answer 5

round()是四舍五入；
trunc()取整数；
ceil()有小数位，就向整数位进一；
format()取成统一格式的字符串.

Answer 6

//四舍五入保留小数点后len位数
function Tsys_njqlrb_f.RoundClassic(R: Real;len:integer): real;
var
  i,j:integer;
  str:string;
begin
  if Trunc(R)=R then
  begin
    Result:= Trunc(R);
    exit;
  end;
  Result:= Trunc(R);
  str:=(copy(floattostr(R),length(inttostr(Trunc(R)))+2,len));
  str:='0.'+str;
  Result:=Result+strtofloat(str);
  j:=1;
  for i:=1 to len do  j:=j*10;
  if length(copy(floattostr(R),length(inttostr(Trunc(R)))+2+len,1))<>0 then
  begin
    if strtoint(copy(floattostr(R),length(inttostr(Trunc(R)))+2+len,1)) >= 5 then
      Result:= Result + 1/j;
  end;
end; 
代码是转摘的，希望能帮到楼主

Answer 7

function DoRound(Value: Extended): Int64; 
  procedure Set8087CW(NewCW: Word); 
  asm
    MOV Default8087CW,AX
    FNCLEX
    FLDCW Default8087CW
  end;
const
  RoundUpCW = $1B32;
var
  OldCW : Word;
begin
  OldCW := Default8087CW; 
  try 
    Set8087CW(RoundUpCW); 
    Result := Round(Value); 
  finally 
    Set8087CW(OldCW); 
  end;
end;

Answer 8

function RoundEx(Value: Extended; RoundMode: TFPURoundingMode = rmUp): Int64;
var
  RM: TFPURoundingMode;
begin
  RM := GetRoundMode;
  try
    SetRoundMode(RoundMode);
    Result := Round(Value);
  finally
    SetRoundMode(RM);
  end;
end;
举例:
i := RoundEx(11.5)    结果: i=12
i := RoundEx(10.5)    结果: i=11

Answer 9

这里的round是四舍六入五成双，也是比较合理的处理小数位的方法，如果楼主要常规的四舍五入的话，就是在第二位为5，而后面没有时，判断一下就好了，其他的都是一样的

Answer 10

function DealPrecision(number:real;precision:integer;dealtype:integer):real;
var
  tmpNumber:real;
  tmpPrecision:integer;
begin
  if Abs(number)<0.0001 then
  begin
    Result:=0;
    Exit;
  end;
  if precision>=0 then
  begin
    Result:=DealPrecisionZ(number,precision,dealtype);
    exit;
  end
  else
  begin
    tmpPrecision:=abs(precision);
    tmpNumber:=number/power(10,tmpPrecision);
    tmpNumber:=DealPrecisionZ(tmpNumber,1,dealtype);
    tmpNumber:=tmpNumber*power(10,tmpPrecision);
    Result:=tmpNumber;
  end;
end;function DealPrecisionZ(number:real;precision:integer;dealtype:integer):real;
var
  s:string;
  i:integer;
  tmp:string;
  strNumber:string;
  intLength,intIntCount,intPointPos,intFloatCount:integer;
  intZFFlag:Integer;
begin
  if Abs(number)<0.0001 then
  begin
    Result:=0;
    Exit;
  end;
  if number<0 then
  begin
    intZFFlag:=-1;
  end
  else
  begin
    intZFFlag:=1;
  end;
  number:=intZFFlag*number;
  strNumber:=floattostr(number);
  if copy(strNumber,1,15)='0.0999999999999' then
  begin
    strNumber:='0.1';
  end;  if pos('.',strNumber)>0 then
  begin
    if pos('0000000000',strNumber)>pos('.',strNumber) then
    begin
      strNumber:=copy(strNumber,1,(pos('0000000000',strNumber)-1));
    end;
  end;  intPointPos:=Pos('.',strNumber);
  if intPointPos=0 then
  begin
    number:=intZFFlag*number;
    result:=number;
    exit;
  end;
  intLength:=length(strnumber);
  intIntCount:=intPointPos-1;
  intFloatCount:=intLength-intPointPos;
  s:='0.';
  for i:=1 to (precision+1) do
  begin
    s:=s+'0';
  end;
  case dealtype of
    0 :
    begin
      number:=StrToFloat(copy(FloatToStr(number),1,intPointPos+(Length(s)-2)));
      tmp:=FormatFloat(s,(number+(5/(power(10,precision+1)))));
      number:=strtofloat(copy(tmp,0,length(tmp)-1));
    end;
    1 :
    begin
      s:='0.';
      for i:=1 to (precision-1) do
      begin
        s:=s+'0';
      end;
      s:=s+'1';
      if precision<intFloatCount then
      begin
        number:=strtofloat(copy(strnumber,0,intIntCount+1+precision))+strtofloat(s);
      end;
    end;
    2 :
    begin
      number:=strtofloat(copy(strnumber,0,intIntCount+1+precision));
    end;
  end;
  number:=intZFFlag*number;
  result:=number;
end;

Answer 11

seleron
 
(旺旺贝贝) 
也出手了呀