/in/foo.c:3:1: error: unknown type name 'bool'
    3 | bool isPrime(int n)
      | ^~~~
/in/foo.c:2:1: note: 'bool' is defined in header '<stdbool.h>'; did you forget to '#include <stdbool.h>'?
    1 | #include <stdio.h>
  +++ |+#include <stdbool.h>
    2 | 
/in/foo.c: In function 'isPrime':
/in/foo.c:5:24: error: 'false' undeclared (first use in this function)
    5 |         if(n<=1)return false;
      |                        ^~~~~
/in/foo.c:5:24: note: 'false' is defined in header '<stdbool.h>'; did you forget to '#include <stdbool.h>'?
/in/foo.c:5:24: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:6:24: error: 'true' undeclared (first use in this function)
    6 |         if(n<=3)return true;
      |                        ^~~~
/in/foo.c:6:24: note: 'true' is defined in header '<stdbool.h>'; did you forget to '#include <stdbool.h>'?
/in/foo.c: At top level:
/in/foo.c:9:9: error: expected identifier or '(' before 'return'
    9 |         return true;
      |         ^~~~~~
/in/foo.c: In function 'main':
/in/foo.c:20:9: warning: implicit declaration of function 'ptintf'; did you mean 'printf'? [-Wimplicit-function-declaration]
   20 |         ptintf("%d is not a primer!\n",n);
      |         ^~~~~~
      |         printf
/in/foo.c: In function 'isPrime':
/in/foo.c:8:9: warning: control reaches end of non-void function [-Wreturn-type]
    8 |         }
      |         ^