/in/foo.c: In function 'main':
/in/foo.c:8:6: warning: 'c' is used uninitialized [-Wuninitialized]
    8 |    if(c == '+')
      |      ^
/in/foo.c:5:14: note: 'c' was declared here
    5 |    int a, b, c;
      |              ^