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The function I want to implement is to filter out specified characters or specify the type of characters used after the user enters any character. Please give instructions, experts!

Last edited by fornever on 2006-9-16 at 22:03 ]

Split the var into two parts. The first part is the first character, and the second part is all the remaining characters. Then judge whether the first character needs to be filtered... Then judge whether the remaining string is empty. If it is not empty, GOTO back to continue the loop.

Re fornever:

What does it mean to filter out the input characters? Does it mean deleting the input characters in a certain text? I don't understand what operation you want to do.

This is like, for example, using the command copy con h.txt or the set /p command to let the user input any characters, and then I filter out specified characters in the background, or it's not filtering, just prompt that which character is not allowed to be used. In short, I need to identify a certain kind of character! Oh, my Chinese is poor, please forgive me!~

re:NaturalJ0
Wondering how to split a string, including numbers, letters, and many symbols, or say, specifying that only a certain type of characters can be used, such as specifying that only letters and numbers can be used,
How to implement it?
Or rely on third-party tools?

set /p var="Please enter from user: "

%var:~0,1% This means the first character of variable var
%var:~1% This means all characters after the first character of variable var

After segmenting, you can do assignment or comparison, etc., and you can use this method to take the first character of the remaining string again. What to do next, I think you will know it yourself.

Hehe. Just learned to check the reply before, but still thank you!
Batch processing is really profound, respect!
Think it's still write the code now:

set /p var=Please enter:
:start
if "%var:~0,1%"=="?" goto error
if "%var:~0,1%"==">" goto error
if "%var:~0,1%"=="<" goto error
if "%var:~0,1%"=="|" goto error
:: if "%var:~0,1%"=="Add filtered characters" goto error
if "var"=="" goto next
set var=%var:~1%
goto start
:next
echo succeed!
goto end
:error
echo error!
:end

Thank you again to the friends who helped!

Batch processing can't detect all characters. When it encounters sensitive characters like |, >, <, etc., it will automatically exit.

...Can the ^ symbol be used? Actually, my purpose is to filter out those characters that are not allowed to be used as file names

Actually, it's still the previous question, but this time the difference is that we need to restrict the characters entered by the user after set /p to be numbers, uppercase and lowercase letters, and a few specific special symbols. Or it's also okay to restrict only one type!

fingstr should be a typo of findstr.

Last time? Where was the last time? If it's not someone who cares, no one will pay attention to what post others posted last time. Hehe, your requirement makes me confused.

I'm sorry, it's indeed
http://www.cn-dos.net/forum/viewthread.php?tid=22897&fpage=1&highlight=
The so-called last time

It means using if and findstr to judge whether there are restricted characters in the input after the user enters the string

I want to use findstr to restrict the data type of the input to uppercase and lowercase letters and numbers
code:

set /p input:
::Write the %input:% type restricted by findstr here
if ....
::This if statement judges whether there are disallowed character types, such as some symbols

findstr "^*$" Judge pure letters
findstr "^*$" Judge pure numbers

@echo off
set/p aa=Enter your code:
echo %aa%|findstr "^*$"||echo ERROR!!!

Just wrote it casually, to judge pure letters, I wonder if the original poster means this???

             FINDSTR正则表达式的基本用法



1.findstr . 2.txt 或 Findstr "." 2.txt  

从文件2.txt中查找任意字符，不包括空字符或空行

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2.findstr .* 2.txt 或 findstr ".*" 2.txt

从文件2.txt中查找任意字符包括空行和空字符

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3.findstr "" 2.txt

从文件2.txt中查找包括数字0－9的字符串或行

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4.findstr "" 2.txt

从文件2.txt中查找包括任意字符的字符串或行

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5.findstr "" 2.txt

从文件2.txt中查找包括a b c e z y字母的字符串或行

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6.findstr "" 2.txt

从文件2.txt中查找小写字符a-f l-z的字符串，但不包含g h I j k这几个字母。

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7.findstr "MY" 2.txt

从文件2.txt中可以匹配 MahY , MbiY, MahY等…..

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8. ^和$符号的应用

^ 表示行首，"^step"仅匹配 "step hello world"中的第一个单词

$ 表示行尾，"step$"仅匹配 "hello world step"中最后一个单词

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9.finstr "" 2.txt

如果是纯数字的字符串或者行便过滤掉，例如2323423423 这样的字符串，如果是345hh888这样的形式就不成了。

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10.findstr "" 2.txt

同上，如果是纯字母的字符串或者行便过滤掉，例如 sdlfjlkjlksjdklfjlskdf这样的字符，如果是sdfksjdkf99999这样的形式，掺杂着数字就不成了

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11.*号的作用

前面已经说过了 ".*"表示搜索的条件是任意字符，*号在正则表达式中的作用不是任何字符，而是表示左侧字符或者表达式的重复次数，*号表示重复的次数为零次或者多次。

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12.findstr "^*$" 2.txt

这个是匹配找到的纯数字，例如 234234234234，如果是2133234kkjl234就被过滤掉了。

   Findstr "^*$" 2.txt

这个是匹配找到的纯字母，例如 sdfsdfsdfsdf，如果是213sldjfkljsdlk就被过滤掉了

如果在搜索条件里没有*号，也就是说不重复左侧的搜索条件，也就是 那只能匹配字符串的第一个字符也只有这一个字符，因为有行首和行尾的限制，"^$"第一个字符如果是数字就匹配，如果不是就过滤掉，如果字符串是 9 就匹配，如果是98或者9j之类的就不可以了。

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13. "\<…\>"这个表达式的作用

这个表示精确查找一个字符串，\<sss 表示字的开始位置，sss\>表示字的结束位置

echo hello world computer|findstr "\<computer\>"这样的形式

echo hello worldcomputer|findstr "\<computer\>" 这样的形式就不成了，他要找的是 "computer"这个字符串，所以不可以。

echo hello worldcomputer|findstr ".*computer\>"这样就可以匹配了

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Here is the translation of the above content:

　　Post a section of the usage of findstr. The original poster can imitate to write a code to restrict the input type:

             Basic Usage of FINDSTR Regular Expressions



1. findstr . 2.txt or Findstr "." 2.txt  

Find any characters from file 2.txt, excluding empty characters or blank lines

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2. findstr .* 2.txt or findstr ".*" 2.txt

Find any characters from file 2.txt including blank lines and empty characters

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3. findstr "" 2.txt

Find strings or lines including numbers 0-9 from file 2.txt

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4. findstr "" 2.txt

Find strings or lines including any characters from file 2.txt

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5. findstr "" 2.txt

Find strings or lines including letters a, b, c, e, z, y from file 2.txt

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6. findstr "" 2.txt

Find strings of lowercase characters a-f and l-z from file 2.txt, but do not include letters g, h, I, j, k.

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7. findstr "MY" 2.txt

Can match MahY, MbiY, MahY, etc. in file 2.txt…..

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8. Application of ^ and $ symbols

^ means the beginning of a line, " ^step" only matches the first word in "step hello world"

$ means the end of a line, "step$" only matches the last word in "hello world step"

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9. finstr "" 2.txt

If it is a pure digital string or line, filter it out. For example, a string like 2323423423, if it is in the form of 345hh888, it is not.

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10. findstr "" 2.txt

Same as above, if it is a pure letter string or line, filter it out. For example, a character like sdlfjlkjlksjdklfjlskdf, if it is in the form of sdfksjdkf99999, mixed with numbers, it is not.

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11. Role of * symbol

As mentioned earlier, ".*" means the search condition is any character. The role of * in regular expressions is not any character, but means the number of repetitions of the left character or expression. * means the number of repetitions is zero or more times.

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12. findstr "^*$" 2.txt

This matches pure numbers found, for example 234234234234, if it is 2133234kkjl234, it is filtered out.

   Findstr "^*$" 2.txt

This matches pure letters found, for example sdfsdfsdfsdf, if it is 213sldjfkljsdlk, it is filtered out.

If there is no * sign in the search condition, that is, not repeating the left search condition, that is,  , it can only match the first character of the string and only this character. Because of the restrictions of the beginning and end of the line, "^$" will match if the first character is a number, and filter out if it is not. If the string is 9, it matches; if it is 98 or 9j, etc., it is not possible.

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13. The role of "\<…\>" expression

This means to accurately find a string. \<sss means the start position of a word, and sss\> means the end position of a word.

echo hello world computer|findstr "\<computer\>" such form

echo hello worldcomputer|findstr "\<computer\>" such form is not, it wants to find the string "computer", so it is not.

echo hello worldcomputer|findstr ".*computer\>" this can match

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