foo.c: In function 'main':
foo.c:6:17: warning: format '%c' expects argument of type 'char *', but argument 2 has type 'int' [-Wformat=]
    6 |         scanf("%c",str[0]);
      |                ~^  ~~~~~~
      |                 |     |
      |                 |     int
      |                 char *
foo.c:6:23: warning: 'str' is used uninitialized [-Wuninitialized]
    6 |         scanf("%c",str[0]);
      |                    ~~~^~~
foo.c:5:10: note: 'str' declared here
    5 |     char str[100];
      |          ^~~

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