buffer problem

[Bouya]

hi

i want make hexdecimal number in a buffer then put them in a char pointer :
like that:

stringstream ss (stringstream::in | stringstream::out);
int a = 0x25;
int b = 0x0c;
char *y = new char;
ss << std::hex << a;
ss << std::hex << b;

ss >> y;

std::cout << y << std::endl;

What i got : 25c
But what i want to get is 250c , i don't know why "0" not added !!

Did any one have idea to have the right result ??
Thanks

[coder777]

You can use setw() and setfill() (with 2/0 instead of that in the example):

http://www.cplusplus.com/reference/iostream/manipulators/setfill/

[BlackSheep]

Why should it write the zero? Do we write 0015? b is just a number, and you're telling your computer to output that number for you.
Use stream manipulators to pad with zeros:

ss<<std::setw(2)<<std::setfill('0');

Setw forces it to print that many characters, and setfill tells it to use that character for padding.

[kbw]

This is really bad:

stringstream ss;
char *y = new char;
//...
ss >> y;

Instead, do this:

ostringstream ss;
//...
std::string str = ss.str();

[Bouya]

the problem that here i know where i have '0' , but in my work , i have variable i don't know when i will got '0' and when not .
i can have 0x00 or 0x05 or 0x20 .....

So how can i solve this problem ?

[kbw]

You're not seeing the leading 0 when you write 0xc because the field width hasn't been set.

See coder777's post above to set the field width and fill character.