【DOS批处理】函数定义和用法

本文主要讲述如下几个问题：

1.什么是函数，怎么创建函数？

2.怎么调用一个函数？

3.函数是怎么工作的？

4.怎么向函数传递参数？

5.函数怎么返回值和返回一个局部变量的值。

一、创建函数（什么是函数）

在batch script 中的函数以一个标签开始，并以goto:eof结束，如下：

script

[plain] view
plaincopy

:myDosFunc - 函数的开始，用一个标签标识

echo. 函数体，可以执行很多命令

echo.

GOTO:EOF

二、调用函数

Script: 01.

call:myDosFunc

三、函数怎么工作

调用函数的脚本将其分成两部分。

1.main script: 从第一行开始并且以 GOTO:EOF命令结束

2.函数部分:由多个函数组成，由main script调用。

SCRIPT：

[plain] view
plaincopy

@echo off

echo.开始调用函数

call:myDosFunc

echo.从函数返回myDosFunc

echo.&pause&goto:eof

::--------------------------------------------------------

::-- 函数部分开始

::--------------------------------------------------------

:myDosFunc - here starts my function identified by it`s label

echo. here the myDosFunc function is executing a group of commands

echo. it could do a lot of things

goto:eof

三、怎么传递参数，并且在函数中获取参数的值

1.用空格或者逗号将参数分开

2.用双引号将带有空格的字符串参数括起来

[plain] view
plaincopy

call:myDosFunc 100 YeePEE

call:myDosFunc 100 "for me"

call:myDosFunc 100,"for me"

获取参数，采用%1~%9来获取每个参数的值。%0,表示批处理文件本身

[plain] view
plaincopy

:myDosFunc - here starts myDosFunc identified by it`s label

echo.

echo. here the myDosFunc function is executing a group of commands

echo. it could do %~1 of things %~2.

goto:eof

带参数的脚本

[plain] view
plaincopy

@echo off

echo.going to execute myDosFunc with different arguments

call:myDosFunc 100 YeePEE

call:myDosFunc 100 "for me"

call:myDosFunc 100,"for me"

call:myDosFunc 100,for me

echo.&pause&goto:eof

::--------------------------------------------------------

::-- Function section starts below here

::--------------------------------------------------------

:myDosFunc - here starts my function identified by it's label

echo.

echo. here the myDosFunc function is executing a group of commands

echo. it could do %~1 of things %~2.

goto:eof

四、函数返回值

1、调用命令不像其他语言那样能有返回值，最常用的做法是在函数中将该值保存在全局变量中，调用结束后

直接用该全局变量。如下：

Usage:

[plain] view
plaincopy

set "var1=some hopefully not important string"

echo.var1 before: %var1%

call:myGetFunc

echo.var1 after : %var1%

Script:

[plain] view
plaincopy

:myGetFunc - get a value

set "var1=DosTips"

goto:eof

脚本输出如下：

var1 before: some hopefully not important string

var1 after : DosTips

2、通过引用返回值，调用者通过传递一个变量给函数来存储返回值

Usage:

[plain] view
plaincopy

call:myGetFunc var1

cho.var1 after : %var1%

Script:

[plain] view
plaincopy

:myGetFunc - passing a variable by reference

set "%~1=DosTips"

goto:eof

脚本输出如下：

var1 after : DosTips

完整脚本：

[plain] view
plaincopy

@echo off

set "var1=CmdTips"

echo.var1 before: %var1%

call:myGetFunc var1

echo.var1 after : %var1%

echo.&pause&goto:eof

::--------------------------------------------------------

::-- Function section starts below here

::--------------------------------------------------------

:myGetFunc - passing a variable by reference

set "%~1=DosTips"

goto:eof

五、函数的局部变量

怎么保证局部变量和全局变量不冲突，SETLOCAL命令能让处理器当做是局部变量，用ENDLOCAL解除局部变量。

ENDLOCAL 会被自动调用，当批处理执行到文件末尾的时候，即GOTO:EOF。SETLOCAL可以很好的保护函数内与外面的变量不会冲突。

[plain] view
plaincopy

@echo off

set "aStr=Expect no changed, even if used in function"

set "var1=No change for this one. Now what?"

echo.aStr before: %aStr%

echo.var1 before: %var1%

call:myGetFunc var1

echo.aStr after : %aStr%

echo.var1 after : %var1%

echo.&pause&goto:eof

::--------------------------------------------------------

::-- Function section starts below here

::--------------------------------------------------------

:myGetFunc - passing a variable by reference

SETLOCAL

set "aStr=DosTips"

set "%~1=%aStr%"

ENDLOCAL

goto:eof

脚本输出：

aStr before: Expect no changed, even if used in function

var1 before: No change for this one. Now what?

aStr after : Expect no changed, even if used in function

var1 after : No change for this one. Now what?

返回局部变量

----怎么跳过ENDLOCAL的屏障，返回局部变量值？

采用”变量扩充“，在SETLOCAL与ENDLOCAL之间的全局变量的值会备份，当退出ENDLOCAL，该值将恢复。让命令处理器来执行ENDLOCAL 和SET命令。

[plain] view
plaincopy

@echo off

set "aStr=Expect no changed, even if used in function"

set "var1=Expect changed"

echo.aStr before: %aStr%

echo.var1 before: %var1%

call:myGetFunc var1

echo.aStr after : %aStr%

echo.var1 after : %var1%

echo.&pause&goto:eof

::--------------------------------------------------------

::-- Function section starts below here

::--------------------------------------------------------

:myGetFunc - passing a variable by reference

SETLOCAL

set "aStr=DosTips"

( ENDLOCAL

set "%~1=%aStr%"

)

goto:eof

:myGetFunc2 - passing a variable by reference

SETLOCAL

set "aStr=DosTips"

ENDLOCAL&set "%~1=%aStr%" &rem THIS ALSO WORKS FINE

goto:eof

脚本输出：

aStr before: Expect no changed, even if used in function

var1 before: Expect changed

aStr after : Expect no changed, even if used in function

var1 after : DosTips

六、编写递归函数

让函数局部变量的变换对调用者是可见的，循环调用函数，让变量可重用。下面编写一个函数计算Fibonacci数列。

[plain] view
plaincopy

@echo off

set "fst=0"

set "fib=1"

set "limit=1000000000"

call:myFibo fib,%fst%,%limit%

echo.The next Fibonacci number greater or equal %limit% is %fib%.

echo.&pause&goto:eof

::--------------------------------------------------------

::-- Function section starts below here

::--------------------------------------------------------

:myFibo -- calculate recursively the next Fibonacci number greater or equal to a limit

:: -- %~1: return variable reference and current Fibonacci number

:: -- %~2: previous value

:: -- %~3: limit

SETLOCAL

set /a "Number1=%~1"

set /a "Number2=%~2"

set /a "Limit=%~3"

set /a "NumberN=Number1 + Number2"

if /i %NumberN% LSS %Limit% call:myFibo NumberN,%Number1%,%Limit%

(ENDLOCAL

IF "%~1" NEQ "" SET "%~1=%NumberN%"

)

goto:eof

七、总结，定义一个标准的dos batch script function

[plain] view
plaincopy

:myFunctionName -- function description here

:: -- %~1: argument description here

SETLOCAL

REM.--function body here

set LocalVar1=...

set LocalVar2=...

(ENDLOCAL & REM -- RETURN VALUES

IF "%~1" NEQ "" SET %~1=%LocalVar1%

IF "%~2" NEQ "" SET %~2=%LocalVar2%

)

GOTO:EOF

版权声明：本文为博主原创文章，未经博主允许不得转载。