#include

<

stdio.h

>

#include

<

stdlib.h

>

void

foo(

void

)

{

printf(

"

into the foo function\n

"

);

return

;

//

结束子函数调用，返回主函数

printf(

"

out the foo function\n

"

);

}

int

main()

{

foo();

printf(

"

Hello world!\n

"

);

return

0

;

}

运行结果: