/in/foo.c: In function 'main':
/in/foo.c:6:17: warning: unknown conversion type character '.' in format [-Wformat=]
    6 |         scanf("%.3f",x);
      |                 ^
/in/foo.c:6:15: warning: too many arguments for format [-Wformat-extra-args]
    6 |         scanf("%.3f",x);
      |               ^~~~~~
/in/foo.c:12:19: warning: implicit declaration of function 'sqr' [-Wimplicit-function-declaration]
   12 |                 y=sqr(5*x+10);}
      |                   ^~~
/in/foo.c:6:9: warning: 'x' is used uninitialized [-Wuninitialized]
    6 |         scanf("%.3f",x);
      |         ^~~~~~~~~~~~~~~
/in/foo.c:5:16: note: 'x' was declared here
    5 |         double x,y;
      |                ^
/usr/bin/ld: /tmp/ccnMZFQ9.o: in function `main':
foo.c:(.text.startup+0x81): undefined reference to `sqr'
collect2: error: ld returned 1 exit status