How can I use a string in a bitmap

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1.00/5 (2 votes)

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i using "gdiplus" library and i have a problem, i want to use string variable inside this variable, i don't know how to call it because i new at this library.

My program is just taking the image.bmp path inside a variable.

C++

string username()
{
    char username[UNLEN + 1];
    DWORD username_len = UNLEN + 1;
    GetUserName(username, &username_len);
    string pcuser = username;
    return pcuser;
}

int main()
{
    Gdiplus::Bitmap bmp("C:\\Users\\" + username() + "\\Documents\\Visual Studio Things\\image.bmp");
    return 0;
}

So, how can i use username() inside a Bitmap ?

What I have tried:

I tried to use .c_str with the username() but this is not working. any suggestions ? I'm getting this error

Error (active) E0289 no instance of constructor "Gdiplus::Bitmap::Bitmap" matches the argument list argument types are: (std::basic_string, std::allocator>)

Posted 10-Nov-19 3:53am

CodingUniversity

Updated 10-Nov-19 20:16pm

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Dave Kreskowiak · Answer 1 · 2019-11-10T05:26:00

Solution 1

[EDIT]
Correction, you're using the wrong terminology.

You don't "use a string in a bitmap". You're trying to use the return value from your username function in a path.

This has nothing to with a Bitmap. This is just string manipulation in C.

For now, simplify what you're doing. Forget the Bitmap junk and stop trying to use as few lines of code as possible. DO NOT DIRECTLY USE THE RETURN VALUE OF A METHOD CALL IN A COMPOUND STATEMENT. You're just making it harder on yourself to debug your code.

Read: https://www.codingame.com/playgrounds/14213/how-to-play-with-strings-in-c/string-concatenation[^]

Posted 10-Nov-19 5:26am

Dave Kreskowiak

Updated 10-Nov-19 5:33am

v3

Comments

[no name] 10-Nov-19 11:26am

Stupid f***ing answer, but thanks! i already success it.

Dave Kreskowiak 10-Nov-19 11:32am

Even dumber question. Your subject line didn't match what you started the question with, not did it match the code you posted.

[no name] 10-Nov-19 11:34am

Yes it is, but you cannot give a simple answer, you are always need to be different and give some stupid functions. (":

Dave Kreskowiak 10-Nov-19 11:36am

You either read up on how to do string manipulation in C and FIGURE IT OUT FOR YOURSELF, or you are forever going to be dependent on other people to write your code for you.

String manipulation is a set of basic techniques that you MUST LEARN if you want any chance at all of succeeding at writing code.

[no name] 10-Nov-19 11:37am

Of course i need that, but not to this specific problem, the answer it just to use wstring instead of string. that's all.

Dave Kreskowiak 10-Nov-19 11:38am

YES, FOR THIS SPECIFIC PROBLEM!!! You're failing at build a path string to pass to the Bitmap constructor!

[no name] 10-Nov-19 11:41am

There is a simple way to solve this.

Dave Kreskowiak 10-Nov-19 13:06pm

Yeah. Write your code so it's easier to debug and inspect variable content before you try to use it.

The different between string and wstring is wstring uses wide-characters (multiple bytes per character) and string doesn't.

I think you would have seen the username come back as a single character and wondered why that was.

[no name] 10-Nov-19 13:08pm

Thank you for your information, i learned something new!

Dave Kreskowiak 10-Nov-19 13:19pm

It's only the same sh*t we've been telling you over and over and over again.

Richard MacCutchan 10-Nov-19 12:35pm

Dave, this person has already been cited for abuse, please just add your vote to OP's page.

[no name] 10-Nov-19 13:00pm

std::cout << "you ugly";

Dave Kreskowiak 10-Nov-19 13:07pm

I'd be happy to.

KarstenK · Answer 2 · 2019-11-10T20:17:00

Solution 2

Very simple code in your main function:

C++

string name = username();
Gdiplus::Bitmap bmp("C:\\Users\\" + name + "\\Documents\\Visual Studio Things\\image.bmp");

Posted 10-Nov-19 20:17pm

KarstenK