应脚本语言版主sdhylj（ss 婶婶^_^）的要求，整理了下用dw返回计算表达式值的相关文档
1、返回比较表达式如60 < 70的函数
函数f_exp_compare
- C/C++ code
//====================================================================// 函数: f_exp_compare//--------------------------------// 描述: 返回比较表达式的结果//--------------------------------// 参数:// value string as_str 表达式，如 60 < 70//--------------------------------// 返回值: string 比较表达试的结果 1为真，0为假，-1为表达式错误//====================================================================String ls_RetDataStore lds_Evaluatelds_Evaluate = CREATE DataStorelds_Evaluate.Create('release 8;~r~ntable()')ls_Ret = lds_Evaluate.Describe("Evaluate('" + "if(" + as_str + ", 1, 0)" + "', 1)")DESTROY lds_EvaluateIF ls_Ret = '!' THEN ls_Ret = '-1'RETURN ls_Ret示例：
- C/C++ code
String ls_Exp, ls_Retls_Exp = '60 < 70'ls_Ret = f_exp_compare(ls_Exp)MessageBox('', ls_Exp + ' --> ' + ls_Ret )2、返回计算表达式如2 * (3+5) + 2^3的函数
- C/C++ code
//====================================================================// 函数: f_exp_ret//--------------------------------// 描述: 返回计算表达式的值//--------------------------------// 参数:// value string as_str 计算表达式，如 2 * (3+5) + 2^3//--------------------------------// 返回值: string 计算表达式的结果值，如果表达式不正确，返回'FALSE'//====================================================================String ls_RetDataStore lds_Evaluatelds_Evaluate = CREATE DataStorelds_Evaluate.Create('release 8;~r~ntable()')ls_Ret = lds_Evaluate.Describe("Evaluate('" + as_str + "', 1)")DESTROY lds_EvaluateIF ls_Ret = '' OR ls_Ret = '!' THEN ls_Ret = 'FALSE'RETURN ls_Ret示例：
- C/C++ code
String ls_Exp, ls_Retls_Exp = '60 * ( 1 + 3 ) + 2^3'ls_Ret = f_exp_ret(ls_Exp)MessageBox('', ls_Exp + ' --> ' + ls_Ret )3、下面是收藏的在SQL中返回计算表达式的函数，但只能算加、减、乘、除，不能算幂：
- SQL code
CREATE FUNCTION dbo.GetExp(@pstrExpress AS VARCHAR(8000))RETURNS DECIMAL(18,6) ASBEGINDECLARE @i INT,@j INT DECLARE @c1 CHAR(1),@c2 CHAR(1),@c VARCHAR(100)DECLARE @v1 DECIMAL(18,6),@v2 DECIMAL(18,6),@v DECIMAL(18,6)DECLARE @t TABLE(ID INT IDENTITY(1,1),s VARCHAR(100))DECLARE @s TABLE(ID INT IDENTITY(1,1),s VARCHAR(100))DECLARE @sv TABLE(ID INT IDENTITY(1,1),v DECIMAL(18,6))SET @pstrExpress = REPLACE(@pstrExpress,' ','')SELECT @i = 0,@j = LEN(@pstrExpress),@c2 = '',@c = ''WHILE @i<@jBEGIN SELECT @c1 = @c2,@i = @i+1 SELECT @c2 = SUBSTRING(@pstrExpress,@i,1) IF CHARINDEX(@c2,'.0123456789') > 0 or (@c2 = '-' and @c1 IN('','*','-','+','/','(')) BEGIN SELECT @c = @c + @c2 CONTINUE END IF @c <> '' BEGIN INSERT @t(s) SELECT @c SELECT @c = '' END IF CHARINDEX(@c2,')')>0 BEGIN INSERT @t(s) SELECT s FROM @s WHERE ID > ISNULL((SELECT MAX(ID) FROM @s WHERE s IN('(')),0) ORDER BY ID DESC DELETE @s WHERE ID >= ISNULL((SELECT MAX(ID) FROM @s WHERE s IN('(')),0) CONTINUE END IF CHARINDEX(@c2,'+-)')>0 BEGIN INSERT @t(s) SELECT s FROM @s WHERE ID > ISNULL((SELECT MAX(ID) FROM @s WHERE s IN('(')),0) ORDER BY ID DESC DELETE @s WHERE ID > ISNULL((SELECT MAX(ID) FROM @s WHERE s IN('(')),0) IF @c2 <> ')' INSERT @s(s) SELECT @c2 CONTINUE END IF CHARINDEX(@c2,'*/')>0 BEGIN INSERT @t(s) SELECT s FROM @s WHERE ID > ISNULL((SELECT MAX(ID) FROM @s WHERE s IN('(','+','-')),0) ORDER BY ID DESC DELETE @s WHERE ID > ISNULL((SELECT MAX(ID) FROM @s WHERE s IN('(','+','-')),0) INSERT @s SELECT @c2 CONTINUE END IF CHARINDEX(@c2,'(')>0 INSERT @s SELECT @c2ENDIF @c <> '' INSERT @t(s) SELECT @cINSERT @t(s) SELECT s FROM @s ORDER BY ID DESCSELECT @i = 0,@j = MAX(ID) FROM @t WHILE @i < @jBEGIN SELECT @i = @i + 1 SELECT @c = s FROM @t WHERE ID = @i IF @c = '(' CONTINUE IF @c NOT IN('*','-','+','/') BEGIN INSERT @sv(v) SELECT CONVERT(float,@c) CONTINUE END SELECT @v2 = v FROM @sv DELETE @sv WHERE ID = (SELECT MAX(ID) FROM @sv) SELECT @v1 = v FROM @sv DELETE @sv WHERE ID = (SELECT MAX(ID) FROM @sv) SELECT @v = CASE @c WHEN '+' THEN @v1 + @v2 WHEN '-' THEN @v1 - @v2 WHEN '*' THEN @v1 * @v2 WHEN '/' THEN @v1 / @v2 END INSERT @sv(v) SELECT @vENDSELECT @v = v FROM @svRETURN @vEND