how to make space in result with c++

A C-like approach was:

...
const int size = 20;
char buffer[size];
int n = snprintf(buffer, size, "%d", c); // use the safe function: snprintf, do not use sprintf
assert(n >= 0);   // format error is indicated by a negative value
assert(n < size); // n is the number of characters written, excluding the terminating null-character
for(int i = 0; i < n; ++i) cout << buffer[i] << ' ';

What it does:
1) write the c into a character array (buffer).
2) make sure you do not write past the buffer end (use snprintf[^])
3) make sure the conversion does not need more characters than provided by the buffer (take in count the return value and assert[^] that writing was not expecting a larger buffer).
4) finally write each character followed by a space

A C++ like approach was to use ostringstream[^].

...
ostringstream oss;
oss << c;
assert(oss.good()); // no format error
// C++11 version
for(char ch: oss.str()) cout << ch << ' ';
// iterator based version
string s = oss.str();
for(string::iterator it = s.begin(); it != s.end(); ++it) cout << *it << ' ';

Cheers
Andi