Testing the File I/O Procedures

CreateFile Program Example
The following program creates a file in output mode, asks the user to enter some text, writes the
text to the output file, reports the number of bytes written, and closes the file. It checks for errors
after attempting to create the file:

TITLE Creating a File (CreateFile.asm)
INCLUDE Irvine32.inc
BUFFER_SIZE = 501
.data
buffer BYTE BUFFER_SIZE DUP(?)
filename BYTE "output.txt",0
fileHandle HANDLE ?
stringLength DWORD ?
bytesWritten DWORD ?
str1 BYTE "Cannot create file",0dh,0ah,0
str2 BYTE "Bytes written to file [output.txt]:",0
str3 BYTE "Enter up to 500 characters and press"
BYTE "[Enter]: ",0dh,0ah,0
.code
main PROC
; Create a new text file.
mov edx,OFFSET filename
call CreateOutputFile
mov fileHandle,eax
; Check for errors.
cmp eax, INVALID_HANDLE_VALUE ; error found?
jne file_ok ; no: skip
mov edx,OFFSET str1 ; display error
call WriteString
jmp quit
file_ok:
; Ask the user to input a string.
mov edx,OFFSET str3 ; "Enter up to ...."
call WriteString
mov ecx,BUFFER_SIZE ; Input a string
mov edx,OFFSET buffer
call ReadString
mov stringLength,eax ; counts chars entered
; Write the buffer to the output file.
mov eax,fileHandle
mov edx,OFFSET buffer
mov ecx,stringLength
call WriteToFile
mov bytesWritten,eax ; save return value
call CloseFile
; Display the return value.
mov edx,OFFSET str2 ; "Bytes written"
call WriteString
mov eax,bytesWritten
call WriteDec
call Crlf
quit:
exit
main ENDP
END main