c++ command line arguments and "^" ?

cyclone3d

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I am looking for a way to be able to input the ^ character without Windows command prompt seeing it as me wanting to input more into the command line.

Even reading the command line directly does not give me the ^ character.

Is it even possible to get around this when using command line arguments for input?
 

cyclone3d

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Can you do the following:

C:\YourProgram.exe "parameter ^"

this will be treated as 1 parameter.

That does work. However, I am wanting to use whatever characters I want as a string input.

If I do something like:

C:\YourProgram.exe "parameter ^"^"

The command prompt reads it as:
C:\YourProgram.exe "parameter ^""
 

cortexodus

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That does work. However, I am wanting to use whatever characters I want as a string input.

If I do something like:

C:\YourProgram.exe "parameter ^"^"

The command prompt reads it as:
C:\YourProgram.exe "parameter ^""

Maybe my approach isn't good but, based on your desired functionality, my first thought is to have the program start, then request the input string, then use some regex to parse it :confused:
 

cyclone3d

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Maybe my approach isn't good but, based on your desired functionality, my first thought is to have the program start, then request the input string, then use some regex to parse it :confused:

Yeah, I know that will work, and is really my preferred method.

I was working on an incomplete program I didn't originally write, came across this, and was trying to figure out how to get around what appears to be a bug in the Windows command line parser.
 

CEpeep

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^ is the escape character for the WinNT and OS/2 command prompt. You literally could not have chosen a worse character to use for input, but it should work if you escape it. Try doing ^^ and see if it works for what you're trying to do.
 

cortexodus

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Yeah, I know that will work, and is really my preferred method.

I was working on an incomplete program I didn't originally write, came across this, and was trying to figure out how to get around what appears to be a bug in the Windows command line parser.

I don't think it's a bug.

From the MSDN link I posted above:
"The caret character (^) is not recognized as an escape character or delimiter. The character is handled completely by the command-line parser in the operating system before being passed to the argv array in the program."
 

cyclone3d

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^ is the escape character for the WinNT and OS/2 command prompt. You literally could not have chosen a worse character to use for input, but it should work if you escape it. Try doing ^^ and see if it works for what you're trying to do.

It is not that I chose the caret character for any specific purpose.

How do you hash a string of characters that has a caret in it if the caret is not able to be input?

The goal is to not have to escape any characters. Everything inside the beginning and end quotes should not have to be escaped.
 

cyclone3d

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I don't think it's a bug.

From the MSDN link I posted above:
"The caret character (^) is not recognized as an escape character or delimiter. The character is handled completely by the command-line parser in the operating system before being passed to the argv array in the program."

It IS being seen as a delimiter of sorts though by the command parser.

If you do:
C:\MyProgram.exe parameter ^

It brings up a prompt asking:
More?

It will then let you input more text.

If you do:
C:\MyProgram.exe parameter ^help
It sees it as:
C:\MyProgram.exe parameter help
 

CEpeep

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I don't think it's a bug.

From the MSDN link I posted above:
"The caret character (^) is not recognized as an escape character or delimiter. The character is handled completely by the command-line parser in the operating system before being passed to the argv array in the program."

This is confusing. They could have written it much better. It's an escape character for the command line, but not a C++ escape character. If you pass an argument to a C++ program through the command line, ^ will be considered an escape character. If you pass data to the program after it is running and prompts for input, ^ will be considered a regular character. If you want to use ^ on the command line, you need to escape it by typing it twice ^^. If you need to feed data on the command line containing ^ you will need to preprocess the data and add an additional escape character first, or alter the program so that it takes input from a file or something instead.
 

cortexodus

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This is confusing. They could have written it much better.

I agree and apologize for not noting the distinction between its relevance to the command line parser and as an argument for a program. Thanks for the taking the time to extrapolate further on this.
 

Dogs

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This is confusing. They could have written it much better. It's an escape character for the command line, but not a C++ escape character. If you pass an argument to a C++ program through the command line, ^ will be considered an escape character. If you pass data to the program after it is running and prompts for input, ^ will be considered a regular character. If you want to use ^ on the command line, you need to escape it by typing it twice ^^. If you need to feed data on the command line containing ^ you will need to preprocess the data and add an additional escape character first, or alter the program so that it takes input from a file or something instead.

In other words, giving the data to the application as a command line parameter is not a great way of doing this. A better way would be to read from standard input once the program has started so that the program is processing the data, not the command line processor. Then you can enter the data after the program has started with the keyboard or use streams and redirection to give it the contents of a text file.

The argv array isn't meant for taking in any arbitrary data you can think of and using it for the program to manipulate. It's used for well defined inputs, like option flags and command line arguments.

Telling the program where the data is -- Good candidate for argv
Pushing the actual data into the program -- Bad candidate for argv
 

cyclone3d

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This is confusing. They could have written it much better. It's an escape character for the command line, but not a C++ escape character. If you pass an argument to a C++ program through the command line, ^ will be considered an escape character. If you pass data to the program after it is running and prompts for input, ^ will be considered a regular character. If you want to use ^ on the command line, you need to escape it by typing it twice ^^. If you need to feed data on the command line containing ^ you will need to preprocess the data and add an additional escape character first, or alter the program so that it takes input from a file or something instead.

Thanks for clearing up how ^ is used in different instances.

MS has horrible documentation on almost everything. I have come to expect nothing more.

Even their sample code they post for download usually has a few program breaking bugs. Some will not even compile without changes to the code.
 

Dogs

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MS has horrible documentation on almost everything. I have come to expect nothing more.

To be fair, their documentation (in this instance) makes complete sense if you think of it as what it is...a piece on parsing command line arguments in C++. The application doesn't delimit on ^ or treat it as a special character when building the argv array. In other words, in the context of your C++ application, ^ is not treated as a special character in any way. This is further clarified immediately afterwards, when they say that the ^ character is "handled completely" by the command line parser.
 

cyclone3d

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To be fair, their documentation (in this instance) makes complete sense if you think of it as what it is...a piece on parsing command line arguments in C++. The application doesn't delimit on ^ or treat it as a special character when building the argv array. In other words, in the context of your C++ application, ^ is not treated as a special character in any way. This is further clarified immediately afterwards, when they say that the ^ character is "handled completely" by the command line parser.

Which is why I said it seems like a bug in the command line parser.

MS would say it is working as designed. I have run across other things that were clearly bugs, and they said the same exact thing.

I know that ^ is not being removed by my program.
 

Dogs

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Which is why I said it seems like a bug in the command line parser.

It's not a bug in the command line parser...It's specified behavior. The MSDN page in question doesn't detail this because it's not a page about the command line. It's a page about handling arguments in C++. The documentation you were looking at doesn't specify this because it's not within the scope of the documentation, not because the documentation is bad.
 

cyclone3d

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It's not a bug in the command line parser...It's specified behavior. The MSDN page in question doesn't detail this because it's not a page about the command line. It's a page about handling arguments in C++. The documentation you were looking at doesn't specify this because it's not within the scope of the documentation, not because the documentation is bad.

I understand why the command line parser handles things like it does, but it could be better.

As for MS' documentation.. There are so many posted documents out there where stuff does not work as documented, especially for certain things having to do with programming.

For that matter, I have also run into documentation from them that is incomplete. For example, they list a class and its members/functions, but don't actually list what the functions do. Yeah, that is real helpful.

Or they give you example code along with a poorly written article and so you download the code to check it out and the code will either not compile or it doesn't work as it should.

I have run into both of these things multiple times when looking up stuff on Microsoft's website. Then I have to go and do one or more searches to actually find out how stuff works from different sources.
 
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Which is why I said it seems like a bug in the command line parser.
...
I know that ^ is not being removed by my program.
I think I can see where the confusion is coming from. There are two parts to this problem: the OS parsing the raw user input to build the command line string, and the program parsing the command line to build the argv array.

The documentation in question only refers to the second half of this process. It's being intentionally vague about the first half, saying only that the caret is "handled" by the OS. That's as much information as a piece of Visual Studio documentation can give, because the nature of this "handling" can (and does) vary between Windows versions.

The goal is to not have to escape any characters. Everything inside the beginning and end quotes should not have to be escaped.
It's unavoidable. You can't put an unescaped quote in a quoted string. This isn't some quirk in the Windows command prompt; it's a fundamental constraint of any delimited data format.
 

cyclone3d

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I think I can see where the confusion is coming from. There are two parts to this problem: the OS parsing the raw user input to build the command line string, and the program parsing the command line to build the argv array.

The documentation in question only refers to the second half of this process. It's being intentionally vague about the first half, saying only that the caret is "handled" by the OS. That's as much information as a piece of Visual Studio documentation can give, because the nature of this "handling" can (and does) vary between Windows versions.


It's unavoidable. You can't put an unescaped quote in a quoted string. This isn't some quirk in the Windows command prompt; it's a fundamental constraint of any delimited data format.

I can too put an unescaped quote in a quoted string. I built a function that does just that in order to get around the default command line parsing of quotes.

The caret on the other hand - no way to get around that that I can tell.
 

CEpeep

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The caret on the other hand - no way to get around that that I can tell.

Simply escape the escape character, as explained earlier. Preprocess your data before feeding it to the program. You can whip up a powershell script that will clean up your input and feed it to your C++ program in a couple minutes if all it needs to do is add ^ in front of every ^.
 
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I can too put an unescaped quote in a quoted string.
Nothing's stopping you from typing "abc"x^z", but the quoted string is terminated by the second quote. The x^z is not quoted in this context, so the caret will not be taken literally (the x^z will resolve to xz).

If you want it to be taken as a single quoted string, you need to double any embedded delimiters (i.e. "abc""x^z").
 
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mikeblas

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If you don't like the way that cmd.exe works, use a different shell; PowerShell doesn't use the up-arrow character as an escape. If you don't the way the C Runtime is chopping up argv, then do it yourself; call the GetCommandLine() to get the command line that was given to the program at its start.
 

cyclone3d

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If you don't like the way that cmd.exe works, use a different shell; PowerShell doesn't use the up-arrow character as an escape. If you don't the way the C Runtime is chopping up argv, then do it yourself; call the GetCommandLine() to get the command line that was given to the program at its start.

Like I said before, it wasn't a program I originally wrote, so it doesn't really matter as I wouldn't normally go the "grab input from the command line" route anyway.

I did actually set it up to use GetCommandLine(), but even then it would still get rid of the caret beforehand. It only helped with the quotes.
 

mikeblas

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That's because the caret is manipulated by the shell. Use a different shell.
 
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