Print given string in all combinations of uppercase and lowercase characters.

Given a string we need to print the string with all possible combinations of the uppercase and lowercase characters in the string.
So given a string "abc", we need to print the following:
ABC
ABc
AbC
Abc
aBC
aBc
abC
abc
Solution is a simple recursive approach where we call the function again and again once with a character in lower case and another time with the same character in upper case. The code is similar to what we would write for all permutations of a string.

void lowerUpper(char *s, int start, int end)
{
    if(start == end)
    {
        cout<<s<<endl;
        return;
    }
    //Change next character to upper case
    s[start] = toupper(s[start]);
    lowerUpper(s,start+1,end);

    //Change the same character as changed earlier to lower case
    s[start] = tolower(s[start]);
    lowerUpper(s,start+1,end);
}