Error(s):

1052291270/source.c:11:20: warning: format specifies type 'char *' but the argument has type 'char (*)[21]' [-Wformat]
     scanf("%s\n", &pole);
            ~~     ^~~~~
1052291270/source.c:20:12: warning: implicitly declaring library function 'isupper' with type 'int (int)' [-Wimplicit-function-declaration]
        if(isupper(pole[i]))
           ^
1052291270/source.c:20:12: note: include the header <ctype.h> or explicitly provide a declaration for 'isupper'
1052291270/source.c:23:23: warning: implicitly declaring library function 'tolower' with type 'int (int)' [-Wimplicit-function-declaration]
            pole[i] = tolower (pole[i]);
                      ^
1052291270/source.c:23:23: note: include the header <ctype.h> or explicitly provide a declaration for 'tolower'
1052291270/source.c:24:28: warning: format specifies type 'char *' but the argument has type 'char' [-Wformat]
            printf("%s\n", pole[i]);
                    ~~     ^~~~~~~
                    %c
1052291270/source.c:42:2: error: expected identifier or '('
*/
 ^
4 warnings and 1 error generated.