中国DOS联盟

Learning batch processing, I learned the set command and was completely confused. I searched in the forum and there are some set-related ones, but after reading them, I still don't understand. I also read the built-in help, but I still don't get it. Does anyone have a better tutorial on set? You can also send a link. Thanks in advance.

Last edited by namejm on 2007-1-20 at 08:07 PM ]

Wherever not understand, put forward it. There must always be someone who can answer it, right?

Let's say it so that we can also learn from it.

Problem 1:
The first line `set a=` means initializing the variable `a` without giving it an initial value. Then `set/p a=请输入关键字……` is used to let the user input a value and assign it to variable `a`. The statement "The set command does not allow variables to contain equal signs" means that if you try to assign a value to a variable using the set command, the value should not contain the equal sign character.

Problem 2:
In `set "STARTPRGNAME=%STARTPRGNAME:"=%"`, `"=%"` is used to remove all double quotes from the variable `STARTPRGNAME`. The `/i` in `if /i "%STARTPRGNAME%" == "cmd" goto :cmd_exe` means case - insensitive comparison. The `:.bat` in `if not "%STARTPRGNAME:.bat=%" == "%STARTPRGNAME%" goto :cmd_or_bat` is used to remove the substring `.bat` from the variable `STARTPRGNAME`. The reason for enclosing `set "STARTPRGNAME=%STARTPRGNAME:"=%"` in quotes is to handle cases where the variable value might contain spaces. `%STARTPRGNAME%` is getting the value of the variable `STARTPRGNAME`, and `%1` is the first command - line argument, they are different in terms of their source (one is a variable, the other is a command - line argument).

Translated:
Problem 1:
The questions are all very basic, hope everyone has a little patience... Hehe.
Problem one:
set a=
set/p a=Please enter the keyword...
start http://www.baidu.com/s?wd=%a%
The built - in help is written like this: SET /P variable=
Why is there nothing on the right side of the equal sign in the first line? Then what is assigned to variable a exactly?
And there is such a sentence: "The set command does not allow variables to contain equal signs" How to understand it?

Problem two:
I saw such a post:
set "STARTPRGNAME=%STARTPRGNAME:"=%"
What does ":=" mean in the statement?

if /i "%STARTPRGNAME%" == "cmd" goto :cmd_exe
What does /i mean in the statement?

if not "%STARTPRGNAME:.bat=%" == "%STARTPRGNAME%" goto :cmd_or_bat
What does .bat mean in the statement?
In the first sentence: Why is the statement after set enclosed in quotes? What does it represent? Also, what does the %STARTPRGNAME on the right side of the equal sign mean? What is assigned to STARTPRGNAME on the left side of the equal sign?
In the second sentence: What is the situation of "%STARTPRGNAME%"? What is the difference between it and %1?

HoHoHo~ I'm more suitable for answering such basic questions.

For question one, just try it yourself. The first sentence originally means to set variable a to empty, so there is naturally nothing on the right side of the equal sign. In fact, it's just deleting variable a. The second sentence means reading the user's input and assigning it to variable a. The sentence "" is a prompt for the user to see. That is, after you execute , the screen displays , and then you enter and press Enter, the value of variable a will be . You can understand it by adding a sentence . The statement that "" is easy to understand. Like the above a is the variable name, can you set a variable named ?

For question two:
You carefully check the help of and will see this sentence , which means replacing all characters or strings in variable with . The help also says that . For example, if the value of variable is , after executing , the value of variable is .
Thus, this sentence can be understood as deleting all quotes in variable and assigning the processed value back to . There are quotes because the character to be processed is a .

Continue. . .
in means case-insensitive. This is easy to understand, you are too lazy, building owner.
The next sentence is the same meaning as the above variable replacement. For example, assume the value of variable is , then ==, which may mean like this (I guess): if it is a.bat file, jump to here .

Answer the last line.
is to expand the value of variable , in fact, it is to read the variable. is just used to represent , because in batch processing, doubling can get one , and means the first parameter of the batch file. You can try creating a new batch file, such as , the file content is only one line , and then call it with the command line to see .

Typing is so tiring~~

Last edited by 0401 on 2007-1-21 at 03:18 AM ]

Thanks to the above - mentioned person for the patient answer, you've worked hard... I understand question one, but you may not have understood my question two.
I'll say it again.
The statement "set "STARTPRGNAME=%STARTPRGNAME:"=%"": What does ":=%" mean?
The statement "if /i "%STARTPRGNAME%" == "cmd" goto :cmd_exe": What does /i mean?
The statement "if not "%STARTPRGNAME:.bat=%" == "%STARTPRGNAME%" goto :cmd_or_bat": What does .bat mean?
All of the above are the contents of a post I saw, and the questions are asked by the person who wrote this post, and my questions are below:
In the first sentence: Why is the statement after set enclosed in quotes? What does it represent? Also, what does the meaning of %STARTPRGNAME on the right side of the equal sign mean? What is assigned to STARTPRGNAME on the left side of the equal sign?
In the second sentence: What's the matter with "%STARTPRGNAME%"?
Especially: What's the difference between it ("%STARTPRGNAME%") and %%1? I didn't see the parameter in the form of "%STARTPRGNAME%" when learning if...
Last edited by hangyug on 2007 - 1 - 20 at 03:50 PM ]

Two Great Secrets:

1. Make good use of the search function

2. Read more help information

.....

@echo off

set STARTPRGNAME=wInG

echo %%STARTPRGNAME%% 变量值为 %STARTPRGNAME%

set STARTPRGNAME=%STARTPRGNAME:G=gzero%

echo %%STARTPRGNAME%% 变量经过字符替换后为 %STARTPRGNAME%

if %STARTPRGNAME%==wingzero echo 看看这句有没有输出

if /i %STARTPRGNAME%==wingzero echo 这句呢？输出了吧。

pause>nul

To the original poster:

I understood your question two in the reply, but you didn't understand my answer.

Then I'll say it again.

Before saying that, I want to tell you that if you can try it yourself, I think you already know why.

My previous answer, I hope you can read it carefully again, I'm just giving an example here.

@echo off

set STARTPRGNAME=wInG

echo %%STARTPRGNAME%% variable value is %STARTPRGNAME%

set STARTPRGNAME=%STARTPRGNAME:G=gzero%

echo %%STARTPRGNAME%% variable after character replacement is %STARTPRGNAME%

if %STARTPRGNAME%==wingzero echo Does this sentence have output

if /i %STARTPRGNAME%==wingzero echo Does this one? It outputs, right.

pause>nul

Enough, original poster, read the above explanation several times. I can't express it any simpler.

BTW: Thanks to redtek for typing for me and adding points, heh heh.

Last edited by 0401 on 2007-1-21 at 06:30 AM ]

Thank you, Brother 0401. It turns out you've answered both my question and the question in the post I cited. Thank you again for your reply...

I also want to thank such a warm - hearted and patient friend!

Learned quite a bit, heh heh, continue...

It is suggested that if you look at several more examples, you will find it very easy to understand.

Also, you need to pay attention that the current selection command is different from the old DOS ones.

It's explained very detailedly, so that we newcomers can understand. Thanks to brother 0401 for his patience and meticulousness!

The explanation about set is very detailed in the 5th floor, and there are examples. A bit better looking

What the person on the 5th floor said is very clear. We beginners can understand it at a glance