/in/foo.c:2:1: error: unknown type name 'bool'
 bool leapyear(int x)
 ^~~~
/in/foo.c: In function 'leapyear':
/in/foo.c:4:21: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(x%400==0||x%4==0&&x%100!=0)
               ~~~~~~^~~~~~~~~~