Convert decimal values to hex and put in a string

[Angus]

Hello

I have an unsigned char[14] and I want to convert the individual array
values into hex and copy to a std::string.

The array does not always hold 14 values - but I do know the length of
the data - obviously up to 14 chars.

An example is an array of six items with decimal values: 0, 10, 228,
164, 72, 11. I want to convert these values to hex and copy to a
string. Eg 000AE4A4480B - which the astute might recognise as a MAC
address.

I tried:

unsigned char cval = 10; // A
std::strstream str;
str << std::hex << cval << std::endl;
std::cout << str.str;

But that outputs 1 for some reason.

As does this:
unsigned char cvals[6];
// populate values
str << std::hex << cvals << std::endl;
std::cout << str.str;

also outputs 1 !

How should I be doing this?

[anon]

Angus wrote:

Hello

I have an unsigned char[14] and I want to convert the individual array
values into hex and copy to a std::string.

The array does not always hold 14 values - but I do know the length of
the data - obviously up to 14 chars.

An example is an array of six items with decimal values: 0, 10, 228,
164, 72, 11. I want to convert these values to hex and copy to a
string. Eg 000AE4A4480B - which the astute might recognise as a MAC
address.

I tried:

unsigned char cval = 10; // A
std::strstream str;
str << std::hex << cval << std::endl;
std::cout << str.str;

But that outputs 1 for some reason.

As does this:
unsigned char cvals[6];
// populate values
str << std::hex << cvals << std::endl;
std::cout << str.str;

also outputs 1 !

How should I be doing this?

Your examples do not compile for me, therefore I have no idea how you
made them output whatever you got there.

[Angus]

On Nov 20, 1:01 pm, anon <[e-mail]:

Angus wrote:

Hello

I have an unsigned char[14] and I want to convert the individual array
values into hex and copy to a std::string.

The array does not always hold 14 values - but I do know the length of
the data - obviously up to 14 chars.

An example is an array of six items with decimal values: 0, 10, 228,
164, 72, 11. I want to convert these values to hex and copy to a
string. Eg 000AE4A4480B - which the astute might recognise as a MAC
address.

I tried:

unsigned char cval = 10; // A
std::strstream str;
str << std::hex << cval << std::endl;
std::cout << str.str;

But that outputs 1 for some reason.

As does this:
unsigned char cvals[6];
// populate values
str << std::hex << cvals << std::endl;
std::cout << str.str;

also outputs 1 !

How should I be doing this?

Your examples do not compile for me, therefore I have no idea how you
made them output whatever you got there.- Hide quoted text -

- Show quoted text -

I meant a std::ostringstream.

I am now doing this:

std::ostringstream strm;
for(int nMAC = 0; nMAC < MACLength; nMAC++)
{
strm << std::hex << std::setw(2) << std::setfill('0')
<< static_cast<int>(byarrMAC[nMAC]);
}

m_strMAC = strm.str();
//convert to uppercase
std::transform(m_strMAC.begin(), m_strMAC.end(), m_strMAC.begin(),
toupper);

And it works.

[anon]

Angus wrote:

On Nov 20, 1:01 pm, anon <[e-mail]:

>Angus wrote:

>>Hello
I have an unsigned char[14] and I want to convert the individual array
values into hex and copy to a std::string.
The array does not always hold 14 values - but I do know the length of
the data - obviously up to 14 chars.
An example is an array of six items with decimal values: 0, 10, 228,
164, 72, 11. I want to convert these values to hex and copy to a
string. Eg 000AE4A4480B - which the astute might recognise as a MAC
address.
I tried:
unsigned char cval = 10; // A
std::strstream str;
str << std::hex << cval << std::endl;
std::cout << str.str;
But that outputs 1 for some reason.
As does this:
unsigned char cvals[6];
// populate values
str << std::hex << cvals << std::endl;
std::cout << str.str;
also outputs 1 !
How should I be doing this?

Your examples do not compile for me, therefore I have no idea how you
made them output whatever you got there.- Hide quoted text -

- Show quoted text -

I meant a std::ostringstream.

I am now doing this:

std::ostringstream strm;
for(int nMAC = 0; nMAC < MACLength; nMAC++)
{
strm << std::hex << std::setw(2) << std::setfill('0')
<< static_cast<int>(byarrMAC[nMAC]);
}

m_strMAC = strm.str();
//convert to uppercase
std::transform(m_strMAC.begin(), m_strMAC.end(), m_strMAC.begin(),
toupper);

And it works.

Sorry, it still does not compile for me.
Check this link:
http://www.parashift.com/c++-faq-lit...t.html#faq-5.8

[David Harmon]

On Tue, 20 Nov 2007 02:35:03 -0800 (PST) in comp.lang.c++, Angus
<an*********@gmail.comwrote,

>str << std::hex << cval << std::endl;
std::cout << str.str;

But that outputs 1 for some reason.

All of the char based stream formatting operators assume that you want
to see the character. To see the number, cast it to an int first.

str << std::hex << (int)cval << '\n';

Don't abuse endl by using it where its special behavior is not needed.

[Angus]

On Nov 20, 4:54 pm, David Harmon <[e-mail]:

On Tue, 20 Nov 2007 02:35:03 -0800 (PST) in comp.lang.c++, Angus
<[e-mail],

str << std::hex << cval << std::endl;
std::cout << str.str;

But that outputs 1 for some reason.

All of the char based stream formatting operators assume that you want
to see the character. To see the number, cast it to an int first.

str << std::hex << (int)cval << '\n';

Don't abuse endl by using it where its special behavior is not needed.

What is wrong with using endl? Most C++ texts use it.