main函数是如何被调用的

When a C program is started by the kernel(by one of the exec functuions),a speical start-up routine is called before the main function is called. The executable program file specifies this start-up routine as the starting address for the program-this is set up by the link editor when it is invoked by the C compiler,usually cc. This start-up routine takes values from the kernel(the command-line arguments and the environment)and sets things up so thar the main function is called as shown earlier.