在文件名中添加唯一的后缀 [英] Add unique suffix to file name
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问题描述
有时候,我需要确保在保存某些数据时不会覆盖现有文件,并且我想使用一个附加类似于浏览器后缀的函数-如果dir/file.txt
存在,它将变为dir/file (1).txt
.
Sometimes I need to ensure I'm not overwriting an existing file when saving some data, and I'd like to use a function that appends a suffix similar to how a browser does it - if dir/file.txt
exists, it becomes dir/file (1).txt
.
推荐答案
这是我制作的使用Qt函数的实现:
This is an implementation I've made, that uses Qt functions:
// Adds a unique suffix to a file name so no existing file has the same file
// name. Can be used to avoid overwriting existing files. Works for both
// files/directories, and both relative/absolute paths. The suffix is in the
// form - "path/to/file.tar.gz", "path/to/file (1).tar.gz",
// "path/to/file (2).tar.gz", etc.
QString addUniqueSuffix(const QString &fileName)
{
// If the file doesn't exist return the same name.
if (!QFile::exists(fileName)) {
return fileName;
}
QFileInfo fileInfo(fileName);
QString ret;
// Split the file into 2 parts - dot+extension, and everything else. For
// example, "path/file.tar.gz" becomes "path/file"+".tar.gz", while
// "path/file" (note lack of extension) becomes "path/file"+"".
QString secondPart = fileInfo.completeSuffix();
QString firstPart;
if (!secondPart.isEmpty()) {
secondPart = "." + secondPart;
firstPart = fileName.left(fileName.size() - secondPart.size());
} else {
firstPart = fileName;
}
// Try with an ever-increasing number suffix, until we've reached a file
// that does not yet exist.
for (int ii = 1; ; ii++) {
// Construct the new file name by adding the unique number between the
// first and second part.
ret = QString("%1 (%2)%3").arg(firstPart).arg(ii).arg(secondPart);
// If no file exists with the new name, return it.
if (!QFile::exists(ret)) {
return ret;
}
}
}
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