Language: C++

#include<bits/stdc++.h>

int main(){
  char S;
  char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
  for(int i=0;i<7;i++){
    if(S==A[i]){
      cout<<i+1;
      break;
    }
  }
}

Compiler output:
a.cc:5:16: warning: multi-character character constant [-Wmultichar]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                ^~~~~
a.cc:5:22: warning: multi-character character constant [-Wmultichar]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                      ^~~~~
a.cc:5:28: warning: multi-character character constant [-Wmultichar]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                            ^~~~~
a.cc:5:34: warning: multi-character character constant [-Wmultichar]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                                  ^~~~~
a.cc:5:40: warning: multi-character character constant [-Wmultichar]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                                        ^~~~~
a.cc:5:46: warning: multi-character character constant [-Wmultichar]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                                              ^~~~~
a.cc:5:52: warning: multi-character character constant [-Wmultichar]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                                                    ^~~~~
a.cc: In function 'int main()':
a.cc:5:16: error: narrowing conversion of '5456212' from 'int' to 'char' [-Wnarrowing]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                ^~~~~
a.cc:5:22: error: narrowing conversion of '4608585' from 'int' to 'char' [-Wnarrowing]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                      ^~~~~
a.cc:5:28: error: narrowing conversion of '5523541' from 'int' to 'char' [-Wnarrowing]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                            ^~~~~
a.cc:5:34: error: narrowing conversion of '5719364' from 'int' to 'char' [-Wnarrowing]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                                  ^~~~~
a.cc:5:40: error: narrowing conversion of '5526853' from 'int' to 'char' [-Wnarrowing]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                                        ^~~~~
a.cc:5:46: error: narrowing conversion of '5066574' from 'int' to 'char' [-Wnarrowing]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                                              ^~~~~
a.cc:5:52: error: narrowing conversion of '5461326' from 'int' to 'char' [-Wnarrowing]
    5 |   char A[100]={'SAT','FRI','THU','WED','TUE','MON','SUN'};
      |                                                    ^~~~~
a.cc:8:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    8 |       cout<<i+1;
      |       ^~~~
      |       std::cout
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~