foo.c:24:1: warning: return type defaults to 'int' [-Wimplicit-int]
 main()
 ^~~~
foo.c: In function 'main':
foo.c:37:1: warning: implicit declaration of function 'system' [-Wimplicit-function-declaration]
 system("pause");
 ^~~~~~

自豪的采用jd5进行评测(github.com/masnn/jd5)