1. gcc demo.c -o demo.out -Wno-implicit-int //do not display this error
2. gcc demo.c -o demo.out -Wno-error=implicit-int // turning this error to a warining
1. gcc demo.c -o demo.out -Wno-implicit-int //do not display this error
2. gcc demo.c -o demo.out -Wno-error=implicit-int // turning this error to a warining