Is there a shorter way to write compound 'if' conditions? [duplicate]

Answer 1

One option is the unordered_set. Put the characters of interest into the set. Then just check the count of the character in question:

#include 
#include 

using namespace std;

int main() {
  unordered_set characters;
  characters.insert('A');
  characters.insert('B');
  characters.insert('C');
  // ...

  if (characters.count('A')) {
    cout << "found" << endl;
  } else {
    cout << "not found" << endl;
  }

  return 0;
}