Substring of char[] in c++

If you need only to read the data then t+i is what you want, alas you'll have to manage the length of your substring...

char *sub = t+i;
int len = j-i;
printf("%.*s\n",len,sub);

If you need to have a distinct copy of the substring, then you must copy.

If you are allowed to modify t, you could set t[j] to 0 and then use t + i to get the substring.

If not, you are going to have to make a copy.

That said, why can't you just use std::string and save yourself the headache?

char* substr(char* arr, int begin, int len)
{
    char* res = new char[len + 1];
    for (int i = 0; i < len; i++)
        res[i] = *(arr + begin + i);
    res[len] = 0;
    return res;
}