/in/foo.c: In function 'main':
/in/foo.c:27:5: warning: implicit declaration of function 'getch' [-Wimplicit-function-declaration]
     getch();
     ^
/tmp/cckKGGwZ.o: In function `main':
foo.c:(.text.startup+0x109): undefined reference to `getch'
collect2: error: ld returned 1 exit status