foo.cc: In function ‘int isprime(int)’:
foo.cc:13:9: warning: ‘k’ may be used uninitialized [-Wmaybe-uninitialized]
   13 |         if(k==n) return 1;
      |         ^~
foo.cc:5:13: note: ‘k’ was declared here
    5 |         int k;
      |             ^
In function ‘int isprime(int)’,
    inlined from ‘int main()’ at foo.cc:24:14:
foo.cc:13:9: warning: ‘k’ may be used uninitialized [-Wmaybe-uninitialized]
   13 |         if(k==n) return 1;
      |         ^~
foo.cc: In function ‘int main()’:
foo.cc:5:13: note: ‘k’ was declared here
    5 |         int k;
      |             ^