GNU make knows how to compile simple C programs without a makefile:
~/tmp/ok$ cat ok.c
~/tmp/ok$ make ok
cc ok.c -o ok
ok.c: In function ‘main’:
ok.c:5: warning: incompatible implicit declaration of built-in function ‘exit’
The argument is the file you want to make, not
the file you want to compile.
PS the warning is because you didn't #include stdlib.h which declares the exit function.