how can we check file existence?
16 次查看(过去 30 天)
显示 更早的评论
hi, i am writing my application(gui app) data to a text file (appdata.txt) and i want to make sure that every time when the application runs it doesn't create a new file or a copy of a file, the problem is:
1) how can i check if the appdata.txt already exists or not (if not then create new text file or else append data to existing one)
thanks for any help.
0 个评论
采纳的回答
Walter Roberson
2011-4-12
if exist('appdata.txt', 'file')
However, the bit about appending suggests that all you really need to do is,
fid = fopen('appdata.txt', 'at');
This will create a new file if needed and append to an existing file if it is there.
1 个评论
Jan
2011-4-12
EXIST(Name, 'file') replies a non-zero number for directories also:
if exist(tempdir, 'file'), disp('found'); end
A better check is:
if exist(Name, 'file') && ~exist(Name, 'dir')
or:
if exist(Name, 'file') == 2
I prefer "fopen(Name, 'r+')", because the append mode needs to locate the end of the file at first, which is time-consuming for large files.
更多回答(2 个)
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Environment and Settings 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!