/in/ex1.c: In function 'main':
/in/ex1.c:36:13: warning: format '%c' expects argument of type 'char *', but argument 2 has type 'int' [-Wformat=]
     scanf("%c",operation);
             ^
/in/ex1.c:37:19: warning: comparison between pointer and integer
     if (operation == "+") {
                   ^~
/in/ex1.c:37:19: warning: comparison with string literal results in unspecified behavior [-Waddress]
/in/ex1.c:40:19: warning: comparison between pointer and integer
     if (operation == "*"){
                   ^~
/in/ex1.c:40:19: warning: comparison with string literal results in unspecified behavior [-Waddress]
/in/ex1.c:36:5: warning: 'operation' is used uninitialized in this function [-Wuninitialized]
     scanf("%c",operation);
     ^~~~~~~~~~~~~~~~~~~~~