foo.c: In function 'main':
foo.c:5:5: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
     scanf("%s", &num);
     ^~~~~
foo.c:5:5: warning: incompatible implicit declaration of built-in function 'scanf'
foo.c:5:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
foo.c:5:13: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'char (*)[15]' [-Wformat=]
     scanf("%s", &num);
            ~^   ~~~~
foo.c:7:9: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
         printf("-");
         ^~~~~~
foo.c:7:9: warning: incompatible implicit declaration of built-in function 'printf'
foo.c:7:9: note: include '<stdio.h>' or provide a declaration of 'printf'
foo.c:19:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("0");
         ^~~~~~
foo.c:19:9: note: include '<stdio.h>' or provide a declaration of 'printf'
foo.c:27:13: warning: incompatible implicit declaration of built-in function 'printf'
             printf("%c", new_num[i]);
             ^~~~~~
foo.c:27:13: note: include '<stdio.h>' or provide a declaration of 'printf'
foo.c:30:5: warning: incompatible implicit declaration of built-in function 'printf'
     printf("\n");
     ^~~~~~
foo.c:30:5: note: include '<stdio.h>' or provide a declaration of 'printf'

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