|
exit好象在stdio.h里面，所以要有包含头文件
return是返回函数调用，如果返回的是main函数，则为退出程序 exit是在调用处强行退出程序，运行一次程序就结束 ------------------------------------------------------------------- return 是返回 函数返回 而exit是退出 ------------------------------------------------------------------- exit(1)表示异常退出.这个1是返回给操作系统的不过在DOS好像不需要这个返回值 exit(0)表示正常退出 ------------------------------------------------------------------- 无论写在那里，都是程序推出，dos和windows中没有什么不一样，最多是系统处理的不一样。 数字0,1,-1会被写入环境变量ERRORLEVEL，其它程序可以由此判断程序结束状态。 一般0为正常推出，其它数字为异常，其对应的错误可以自己指定。 ------------------------------------------------------------------- 返回给操作系统的,0是正常退出,其他值是异常退出,在退出前可以给出一些提示信息,或在调试程序中察看出错原因. ------------------------------------------------------------------- Run-Time Library Reference exit, _exit Terminate the calling process after cleanup (exit) or immediately (_exit). void exit( int status ); void _exit( int status ); Parameter status Exit status. Remarks The exit and _exit functions terminate the calling process. exit calls, in last-in-first-out (LIFO) order, the functions registered by atexit and _onexit, then flushes all file buffers before terminating the process. _exit terminates the process without processing atexit or _onexit or flushing stream buffers. The status value is typically set to 0 to indicate a normal exit and set to some other value to indicate an error. Although the exit and _exit calls do not return a value, the low-order byte of status is made available to the waiting calling process, if one exists, after the calling process exits. The status value is available to the operating-system batch command ERRORLEVEL and is represented by one of two constants: EXIT_SUCCESS, which represents a value of 0, or EXIT_FAILURE, which represents a value of 1. The behavior of exit, _exit, _cexit, and _c_exit is as follows. Function Description exit Performs complete C library termination procedures, terminates the process, and exits with the supplied status code. _exit Performs quick C library termination procedures, terminates the process, and exits with the supplied status code. _cexit Performs complete C library termination procedures and returns to the caller, but does not terminate the process. _c_exit Performs quick C library termination procedures and returns to the caller, but does not terminate the process. When you call the exit or _exit functions, the destructors for any temporary or automatic objects that exist at the time of the call are not called. An automatic object is an object that is defined in a function where the object is not declared to be static. A temporary object is an object created by the compiler. To destroy an automatic object before calling exit or _exit, explicitly call the destructor for the object, as follows: myObject.myClass::~myClass(); You should not call exit from DllMain with DLL_PROCESS_ATTACH. If you want to exit the DLLMain function, return FALSE from DLL_PROCESS_ATTACH. Requirements Function Required header Compatibility exit <process.h> or <stdlib.h> ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP _exit <process.h> or <stdlib.h> Win 98, Win Me, Win NT, Win 2000, Win XP For additional compatibility information, see Compatibility in the Introduction. Libraries All versions of the C run-time libraries. Example /* EXITER.C: This program prompts the user for a yes * or no and returns an exit code of 1 if the * user answers Y or y; otherwise it returns 0. The * error code could be tested in a batch file. */ #include <conio.h> #include <stdlib.h> void main( void ) { int ch; _cputs( "Yes or no? " ); ch = _getch(); _cputs( "\r\n " ); if( toupper( ch ) == 'Y ' ) exit( 1 ); else exit( 0 ); } |
|
|
