如何检查tk_getOpenfile是否实际打开文件？

Question

我的程序的这一部分打开一个文件，下载到扫描仪上进行刷新。如果我刚刚关闭了文件选择窗口，我收到此错误消息 -

wrong # args: should be cksum ?-format string? -channel chan | -filename file | string 
wrong # args: should be cksum ?-format string? -channel chan | -filename file | string 
    while executing 
"::crc::cksum -file $file2program" 


set file2program [tk_getOpenFile] 

## determine chsum 
set filechecksum1 [::crc::cksum -file $file2program] 
set filechecksum [format %X [scan $filechecksum1 %d]] 
.flashutility.messagearea insert end "Checksum for binary file = $filechecksum\n" 
.flashutility.messagearea see end 
set filesize [file size $file2program] 
.flashutility.messagearea insert end "Size of the file to transfer is $filesize bytes\n" 
.flashutility.messagearea see end 
update 

Answer 1

tk_getOpenFile命令不会打开该文件。它返回要打开的文件的全限定名称。如果用户取消，则返回空字符串，这与任何平台上的任何完全限定的文件名都不相同。