控制台输出就象dos下的输出,可不是图形界面。象ping/ipconfig/ftp等命令都是这类程序。
回忆过去,在dos下进行文件操作时,常用到“文件把柄”的概念,使用文件把柄操作时,非常方便,操作时,只要知道把柄号就可以,而不用操心文件的位置。dos下,设备也都有自己的专用把柄,这些把柄是: 0000H 标准输入设备 (stdin) 0001H 标准输出设备 (stdout) 0002H 标准错误设备 (stderr) 0003H 标准辅助设备 (stdaux) 0004H 标准打印设备 (stdprn)
stdin和stdout可以被再定向,dos下常用的“输入改向”和“输出改向”就是这个意思。
下面的dos功能调用中将向屏幕输出信息: mov ah,40h ;写到文件或设备 mov bx,1 ;标准输出设备 lea dx,OutData ;DS:DX->要输出的数据 mov cx,Count ;要输出字符的个数 int 21h ;执行dos功能调用 利用同样的道理,在windows下,也可向屏幕输出信息。这要用到两个Api函数,一个是GetStdHandle,另一个是WriteFile,在Win32 developer's References中它们是这样定义的: ------------------------------------------------------------ HANDLE GetStdHandle( DWORD nStdHandle // input, output, or error device );
The GetStdHandle function returns a handle for the standard input, standard output, or standard error device.
nStdHandle->Specifies the device for which to return the handle. This parameter can have one of the following values: Value | Meaning --------------------+--------------------------- STD_INPUT_HANDLE | Standard input handle STD_OUTPUT_HANDLE | Standard output handle STD_ERROR_HANDLE | Standard error handle
If the function succeeds, the return value is a handle of the specified device. ------------------------------------------------------------ BOOL WriteFile( HANDLE hFile, // handle to file to write to LPCVOID lpBuffer, // pointer to data to write to file DWORD nNumberOfBytesToWrite, // number of bytes to write LPDWORD lpNumberOfBytesWritten, // pointer to number of bytes written LPOVERLAPPED lpOverlapped // pointer to structure needed for overlapped I/O );
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;下面我们看一个程序,作用是显示一个字符串信息!
.386 .model flat,stdcall option casemap:none
include windows.inc
include kernel32.inc include user32.inc
includelib kernel32.lib includelib user32.lib
.data mess db 'How are you !',0 ;要显示的信息
.data? StdOut dd ? ;存放标准输出的把柄 CharOut dd ? ;记录实际输出的字符数
.code start: invoke GetStdHandle,STD_OUTPUT_HANDLE ;获取标准输出的把柄 mov StdOut,eax ;保存把柄号
lea eax,mess invoke lstrlen,eax ;求字符串的长度
lea ecx,CharOut invoke WriteFile,StdOut,addr mess,eax,ecx,NULL ;写文件 invoke ExitProcess,NULL ;程序结束 end start -------------------------------------------------------------- 编译链接,下面给出详尽的信息,供分析参考: D:/MASM7>dir /ad
Volume in drive D has no label Volume Serial Number is 18F0-186B Directory of D:/MASM7
. 〈DIR〉 02-12-03 17:36 . .. 〈DIR〉 02-12-03 17:36 .. LIB 〈DIR〉 02-12-03 17:38 LIB INCLUDE 〈DIR〉 02-12-03 17:38 INCLUDE 0 file(s) 0 bytes 4 dir(s) 2,411,925,504 bytes free
D:/MASM7>ml /coff /I include 4.asm /link /subsystem:console /libpath:lib Microsoft (R) Macro Assembler Version 6.14.8444 └─ 控制台程序 Copyright (C) Microsoft Corp 1981-1997. All rights reserved.
Assembling: 4.asm Microsoft (R) Incremental Linker Version 5.12.8078 Copyright (C) Microsoft Corp 1992-1998. All rights reserved.
/subsystem:console /libpath:lib "4.obj" "/OUT:4.exe"
D:/MASM7>4 How are you ! D:/MASM7> -------------------------------------------------------------- 另外,在masm32.inc中有函数StdOut的声明,可用来直接输出信息,把上面的例子修改后就是下面的样子,可见来得更简炼,供大家参考:
.386 .model flat,stdcall option casemap:none ;case sensitive
include windows.inc
include kernel32.inc include masm32.inc
includelib kernel32.lib includelib masm32.lib
.data mess db 'How are you !',0
.code start: invoke StdOut,addr mess invoke ExitProcess,NULL end start
 
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