how to make a char uppercase in c++ code example

Example 1: c++ char to uppercase

char choice; 
// it will instantly transform it to upper case without the need
// to convert it to int first
choice = (char)toupper(choice);

Example 2: convert all characters in string to uppercase c++

transform(str.begin(), str.end(), str.begin(), ::toupper);

Example 3: uppercase capitalise character in string c++

str[i] = toupper(str[i]);