用于删除后缀的正则表达式

Question

What is the regular expression for removing the suffix of file names? For example, if I have a file name in a string such as "vnb.txt", what is the regular expression to remove ".txt"? Thanks.

Answer 1

Do you really need a regular expression to do this? Why not just look for the last period in the string, and trim the string up to that point? Frankly, there's a lot of overhead for a regular expression, and I don't think you need it in this case.

As suggested by tstenner, you can try one of the following, depending on what kinds of strings you're using:

std::strrchr

std::string::find_last_of

First example:

char* str = "Directory/file.txt";

size_t index;
char* pStr = strrchr(str,'.');
if(nullptr != pStr)
{
    index = pStr - str;
}

Second example:

int index = string("Directory/file.txt").find_last_of('.');

Answer 2

If you're looking for a solution that will give you anything except for the suffix, you should use string::find_last_of .

Your code could look like this:

const std::string removesuffix(const std::string& s) {
  size_t suffixbegin = s.find_last_of('.');

  //This will handle cases like "directory.foo/bar"
  size_t dir = s.find_last_of('/');
  if(dir != std::string::npos && dir > suffixbegin) return s;
  if(suffixbegin == std::string::npos) return s;
  else return s.substr(0,suffixbegin);
}

If you're looking for a regular expression, use \\.[^.]+$ .
You have to escape the first . , otherwise it will match any character, and put a $ at the end, so it will only match at the end of a string.

Answer 3

如果已经使用Qt，则可以使用QFileInfo ，并使用baseName（）函数仅获取名称（如果存在），或使用suffix（）函数获取扩展名（如果存在）。

Answer 4

Different operating systems may allow different characters in filenams, the simplest regex might be (.+)\\.txt$ . Get the first capture group to get the filename sans extension.