• 0

String += appending ASCII value instead of char


Question

I've been experimenting with visual C++ having worked in Java for a while. Right now I'm working with a little String manipulation.

I have a Windows Form with a textBox that displays the value of a String. I'm trying to append a char to the String. The problem I'm having is the ASCII value of the String is appended instead of the char itself. So far I haven't been able to find a solution through the resources I've read. Here is an example:

String^ mystring;

char y = 'd';

mystring = "Test";

mystring += y;

textBox->Text = mystring;

The output is "Test100" instead of "Testd" (100 being the ASCII value of d). What should I be doing differently?

10 answers to this question

Recommended Posts

  • 0

I think you will need to do something like this:

mystring += "" + y;

I don't have a compiler in front of me, but you could also try casting y to a string e.g.:

mystring += (string) y;

EDIT: Whoops, just realised this is Visual C++, not C#. Not sure if either of these things will work.

  • 0

It may be that the reason you're seeing the decimal value instead of the ASCII character is because char is a decimal type. It is a decimal type just large enough to hold an ASCII character: 8-bits. Try referencing it as a pointer instead of a single character to make it a C-style string.

  • Like 1
  • 0

Is 'String' a Microsoft-centric data type or did you mistype the name of the standard 'string' class? The string class in the standard library can append single characters, C-style strings, and standard strings using the '+=' operator.

Without knowing the data type of 'textBox->Text', I'm assuming that something like the following will work:


std::string mystring;
char y = 'd';

mystring = "Test";
mystring += y;
textBox->Text = mystring.c_str();
[/CODE]

Alternatively, you could forgo the niceness of the string class and use only C-style strings. Your example would then look something like this:

[CODE]
char mystring[50];
char y = 'd';

strcpy( mystring, "Test" );
strncat( mystring, &y, 1 );
textBox->Text = mystring;
[/CODE]

  • Like 1
  • 0

String^ mystring;
char y = 'd';
mystring = "Test";
mystring += y;
textBox->Text = mystring;[/CODE]

This is C++/CLI. The caret "^" on a type name is not C++ syntax, it denotes a managed type, here System::String. If you want to learn C++, make sure you create an empty C++ project, not a "CLR" project. You won't be able to work directly with Winforms with C++; if working with Winforms is what you want, learn C# instead. I strongly doubt you want to learn C++/CLI, it is more complicated than you can imagine and it doesn't serve much purpose besides building bridges between the native and the managed world.

Anyway, with System::String you can't append a char to a string using the += operator, however you could call ToString() on the character and append that isntead, i.e.

[CODE]mystring += y->ToString();[/CODE]

But really, run from C++/CLI while there is still time. File -> New -> Project -> Visual C++ -> General -> Empty Project. Now you're doing real, ISO C++. It's complicated enough by itself.

  • 0

.NET uses unicode characters. Use wchar_t instead of char.

wchar_t y = L'd';[/CODE]

It most likely chooses int (System::Int32) as the closest conversion for char as a result, resulting in the decimal number.

If you really want to use char throughout your code, then you can do something similar to Dr_Asik's suggestion by using Convert::ToString:

[CODE]char y = 'd';
String ^value = Convert::ToString(y);[/CODE]

This link explains the mapping of types to the CLI: http://www.c-sharpcorner.com/uploadfile/b942f9/cppcli-for-the-C-Sharp-programmer/ , which is why it maps to a number rather than a character (it does not widen to the number, rather it widens to an integer).

  • Like 1
  • 0

Scrapped everything and redid the project in C#. Holy crap was it easier. I was thinking I could do it in C++ since that's what I used in college (command line progs only). That Visual C++/CLI stuff sucked. Knowing Java I was pretty much able to code in C# without having to look up much of anything. Came up with this little Class for creating a password:


class SecurePassword
{
private String password;
private int length;
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
Random random = new Random();
public void generatePassword(bool useUpper, bool useNumber)
{
char ch;
int i;
int type;
password = "";
for (i = 0; i < this.length; i++)
{
type = (random.Next(0, 4));
if (type == 0 && useUpper)
ch = getRandomUpperChar();
else if (type == 1 && useNumber)
ch = getRandomDigit();
else
ch = getRandomLowerChar();

password += ch;
}
}
public char getRandomDigit()
{
byte[] byteCh = new byte[4];
double range;
uint intCh;
rng.GetBytes(byteCh);
intCh = BitConverter.ToUInt32(byteCh, 0);
range = intCh / 4294967296.0;
intCh = (uint)(range * 10);
return Convert.ToChar(intCh + 48);
}
public char getRandomLowerChar()
{
byte[] byteCh = new byte[4];
double range;
uint intCh;
rng.GetBytes(byteCh);
intCh = BitConverter.ToUInt32(byteCh, 0);
range = intCh / 4294967296.0;
intCh = (uint)(range * 26);
return Convert.ToChar(intCh + 97);
}
public char getRandomUpperChar()
{
byte[] byteCh = new byte[4];
double range;
uint intCh;
rng.GetBytes(byteCh);
intCh = BitConverter.ToUInt32(byteCh, 0);
range = intCh / 4294967296.0;
intCh = (uint)(range * 26);
return Convert.ToChar(intCh + 65);
}
public String getPassword()
{
return password;
}
public void setLength(int len)
{
length = len;
}
}
[/CODE]

Had a little hiccup converting the byte array to a character in the range I wanted, Im sure my solution is a bit sloppy. I wanted to use the secure random methods instead of just Random.Next(min, max).

  • 0
  On 02/10/2012 at 19:21, Lord Method Man said:

Had a little hiccup converting the byte array to a character in the range I wanted, Im sure my solution is a bit sloppy. I wanted to use the secure random methods instead of just Random.Next(min, max).

Note: you're still using Random.Next(...) in your main loop.

Also, you could probably simplify the code a lot with your bytes-to-number conversion being extracted into a separate function.

private char getCharacter(uint start, uint range)
{
    byte[] bytes = new byte[1];

    // realistically, given the expected ranges (not even a full byte), you could use a single byte
    rng.GetBytes(bytes);

    return Convert.ToChar(start + bytes[0] % range);
}
[/CODE]

Any random lowercase character: [code]ch = getCharacter((uint)'a', 26);

Any random uppercase character:

ch = getCharacter((uint)'A', 26);

Any random number character:

ch = getCharacter((uint)'0', 10);

This topic is now closed to further replies.
  • Posts

    • Watchdog finds Microsoft guilty of confusing advertising when it comes to Copilot by Usama Jawad While Microsoft is advocating for Copilot usage in both personal and enterprise environments as much as possible, it arguably hasn't made as big of a splash as it wanted. Now, the U.S. watchdog National Advertising Division (NAD) has criticized Microsoft for some of its advertising practices when it comes to Copilot. In a recent blog post spotted by The Verge, NAD noted that Copilot does possess the functionalities that Microsoft expressly claims it does in enterprise use cases. This includes capabilities like summarization of content, generating text, and creating outlines for PowerPoint slide decks. While Copilot does have some limitations in this area, NAD thinks that they are pretty minor, so the lack of disclosure in this area doesn't really impact how most customers leverage Copilot. That said, the watchdog discovered some problems in Microsoft's messaging when it came to Business Chat. It believes that Redmond's universal and interchangeable use of Copilot for both the assistant and Business Chat can cause confusion among users, as they judge their functionalities. For example, NAD argues that while Copilot is quite fast at seamlessly generating documents in other applications, this is not the case with Business Chat, which requires more manual steps, and this is not abundantly clear in the advertising on Microsoft's website. Finally, NAD advised Microsoft to get rid of its claims regarding an increase in productivity and ROI because while the tech giant does have supporting studies to back its boasts, they do not provide a "good fit" for objective claims. It's also worth highlighting that the UK government recently did trial Copilot in work environments and discovered that participants did save 26 minutes per day on average. Still, it seems like this is not good enough for NAD. Interestingly, Microsoft did respond to NAD's advisory, saying that while it disagrees with some of the watchdog's findings, it has made changes to its advertising messages in order to comply with NAD's recommendations. Source: NAD via The Verge
    • My new emergency poo ticket holder
    • These are the same ignorant, gullible, cowardly fools who still believe that gods are real and that fictional White Jesus is coming back to Earth "any day now". It's a Venn-diagram of two almost perfectly concentric circles. In short, they'll buy anything you lie to them about as long as it makes them less afraid... Of things the rest of us know we don't have to be afraid of at all.
    • It isn't fair to shift all blame to the user. Yes, the user shouldn't have blindly trusted MS with all their data, but assuming the facts reported are correct, MS massively screwed up too. Both can be true.
    • How about with add up/down votes on posts instead? Then we could upvote posts that are True based on the facts and supported by evidence. And we could also downvote the ridiculous paranoid rantings of ignorant, gullible, cowardly people who still fall for ancient proven lies and obvious fearmongering scams behind such nonsense like white supremacy, Nazism, Trumpism, etc. I'm willing to give it a try. How about you?
  • Recent Achievements

    • Experienced
      dismuter went up a rank
      Experienced
    • One Month Later
      mevinyavin earned a badge
      One Month Later
    • Week One Done
      rozermack875 earned a badge
      Week One Done
    • Week One Done
      oneworldtechnologies earned a badge
      Week One Done
    • Veteran
      matthiew went up a rank
      Veteran
  • Popular Contributors

    1. 1
      +primortal
      699
    2. 2
      ATLien_0
      268
    3. 3
      Michael Scrip
      211
    4. 4
      +FloatingFatMan
      186
    5. 5
      Steven P.
      142
  • Tell a friend

    Love Neowin? Tell a friend!