qDebug string display

[zgulser]

Hi,

I have a function like the following;

QString LoggerManager::encryptAes(const char* p_Text, const char* p_key)
{
        ...
 
	unsigned char* text = new unsigned char((strlen(p_Text) - 1)*sizeof(char));
 
	for(int i=0; i < (strlen(p_Text) - 1); i++)
	{
		text[i] = p_Text[i];
	}
 
        ...
 
       qDebug() << "TextManip 2: " << QString((char*)(text));
}

QString LoggerManager::encryptAes(const char* p_Text, const char* p_key)
{
        ...
        
	unsigned char* text = new unsigned char((strlen(p_Text) - 1)*sizeof(char));

	for(int i=0; i < (strlen(p_Text) - 1); i++)
	{
		text[i] = p_Text[i];
	}
       
        ...

       qDebug() << "TextManip 2: " << QString((char*)(text));
}

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p_Text is "ZEROZEROZEROPC010101". But when I want to print it to VS output with qDebug like;

qDebug() << "TextManip 2: " << QString((char*)(text));

qDebug() << "TextManip 2: " << QString((char*)(text));

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the string is printed to output window as;

"ZEROZEROZEROPC010101?????????"

Any ideas?

Regards

[wysota]

Did you null-terminate your string?

[high_flyer]

Try to explicitly add a terminating null character '\0' after the last char of your string in the for loop - i.e p_Text[strlen(p_Text)] = '\0';

[zgulser]

Hi,

It's a c-string. So it should have a null character at the end right?

[high_flyer]

Should and does may differ - as you are manipulating the string.
Besides, you are not allocating a C string, you are allocating a char array - its not the same thing!

[Lesiok]

Hi,

It's a c-string. So it should have a null character at the end right?

But You don't copy null character. Look at the condition of the loop execution.

[zgulser]

Yeap... That's why I don't understand why ???????? is appended to the end. The null character should be put at the end of c-strings.

[high_flyer]

The null character should be put at the end of c-strings.

But you are not allocating a C string!
And we don't know how p_Text is allocated or initialized!

[wysota]

Yeap... That's why I don't understand why ???????? is appended to the end.

There is no such thing as a "C string". You have an array of characters that contain textual data. All functions that work on such data expect them to be null terminated and nobody is going to magically discover that if you copy 10 bytes somewhere, you actually want to null-terminate them.

The null character should be put at the end of c-strings.

That's true. And since you didn't put that null character there, you should now correct your error.

[zgulser]

Ok..

I corrected by putting '\0' at the end.

However, if I put this,

openssl's

AES_encrypt((unsigned char*)text, (unsigned char*)enc_out, &enc_key);

AES_encrypt((unsigned char*)text, (unsigned char*)enc_out, &enc_key);

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doesn't work. I mean enc_out returns "". But if I remove '\0' from text, enc_out returns as expected but with ???????? at the end.

---

Added after 9 minutes:

Ok,

Adding '\0' at the end of enc_out solved the problem.

Thanks for your help.