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This is code from an elder in the forum, but I don't know how to use it, so I've been unable to use it. Which expert can explain it? It's best to explain in detail things like:!num!,!ii:~0,1!. How is! used? This %ii:~0,1% can be found in set /?, but does it mean the same if it's changed to!ii:~0,1!?

Last edited by yardian on 2006-10-21 at 00:16 ]

@echo off

set /p ii=请输入字符串:

setlocal enabledelayedexpansion

set form=0

set ii=%ii%@

:go

if not "%ii:~0,1%"=="@" (

    if /i "!ii:~0,3!"=="yes" set form=1

    set ii=%ii:~1%

    goto go

)

cls

if "%form%"=="1" (

    echo yes

) else (

    echo no

)

pause

You look at this paragraph which is easier to understand.

@echo off

set /p ii=Please enter a string:

setlocal enabledelayedexpansion

set form=0

set ii=%ii%@

:go

if not "%ii:~0,1%"=="@" (

    if /i "!ii:~0,3!"=="yes" set form=1

    set ii=%ii:~1%

    goto go

)

cls

if "%form%"=="1" (

    echo yes

) else (

    echo no

)

pause

@echo %dbg% off && setlocal enabledelayedexpansion

set /p ii=请输入字符串:

set  ii=%ii:*yes=氵%  &&  set  ii=%ii:~0,1%

if /i "!ii!"=="氵" (echo 发现yes字符!) else (echo 没有发现yes字符.)

There is also a stupid method: )
Use the pre - defined strings to be searched by you,
Replace the same strings in the user - input content with them,
Replace them with a flag character that is not easy or unlikely for the user to appear,
Compare this character (replaced as the first character) with a pre - defined symbol (such as "氵"),
If there is this symbol, it means that the replacement is successful, which means that the user - input content contains YES,
If there is no this symbol, it means that the replacement is not successful, so it does not contain.
……

@echo %dbg% off && setlocal enabledelayedexpansion

set /p ii=Please enter a string:

set  ii=%ii:*yes=氵%  &&  set  ii=%ii:~0,1%

if /i "!ii!"=="氵" (echo Found the yes character!) else (echo Did not find the yes character.)

Last edited by redtek on 2006 - 10 - 21 at 08:00 ]

Originally posted by yardian at 2006-10-20 22:38:
:!num!,!ii:~0,1!.
How is ! used? This %ii:~0,1%, can be found from set /?. But does it mean the same when changing to !, like !ii:~0,1!?

%ii:~0,1% (meaning: take the first character of the %ii% variable, starting from offset 0)
　　　　　　(its specific meaning needs to be queried in for /?, this FOR help is very comprehensive)
　　　　　　(there are many kinds of usages, very many, a lot of words can't finish, need to run one by one according to the help to understand)

For other contents, please query the following help information:

SET /?

FOR /?

SETLOCAL /?

IF /?

Among them, FOR has detailed instructions on the use of the! symbol, but it also needs to be repeatedly understood and run and tested : )
Otherwise, it cannot be thoroughly understood : )

Originally posted by pengfei at 2006-10-21 05:11 AM:
You can see this paragraph is easier to understand.

@echo off

set /p ii=Please enter the string:

setlocal enabledelayedexpansion

set form=0

set ii=%ii%@

:go

if not "%ii:~0,1%"=="@" (

     ... 



Looking at this, I feel that !=%,., but why use! instead of %?

`setlocal /?` for a clearer view

Originally posted by yardian at 2006-10-21 11:09:



Looking at this, it doesn't equal !=%,. But why use ! instead of %?

This ! and % can't be fully explained in a few sentences.

The difference between ! and % and when to use them can't be intuitively determined,
Not entirely because their help isn't clearly written,
The main problem is:

　　　　If there are complex assignments of various variables in SET, and values need to be passed during assignment.
　　　　And if you encounter assigning values to variables in a for loop, and the values to be assigned are variables...
　　　　A large number of variables are used inside and outside the FOR, assigning values to each other, passing values...
　　　　There are also a large number of letter or variable separation operations, operating inside or outside the for...
　　　　There are also differences between SET /A and SET A=B similar assignments, etc...
　　　　
And so on. If you usually only write a few batch processing or use them very little,
Then the problem of! and % may not be encountered often, or if encountered, you don't know how to solve the problem of! and %,
The main reason is:

　　　　The above series of contents are interconnected. If you learn DOS too fast, you may have lost or not thoroughly studied before starting to compile more advanced contents.

　　　　Jumping learning and too fast learning speed, and sometimes we often ignore the most basic contents such as SET FOR in order to save time,
　　　　Resulting in the more you learn and apply later, the more proficient the basic knowledge points required are :）

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