In my C++ program, I have the string
string s = "/usr/file.gz";
Here, how to make the script to check for .gz extention (whatever the file name is) and split it like "/usr/file"?
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stackoverflow.com/a/874160/276994Vlad– Vlad2012-05-10 10:48:00 +00:00Commented May 10, 2012 at 10:48
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@Vlad you should close vote, instead of linkingShiplu Mokaddim– Shiplu Mokaddim2012-05-10 10:50:50 +00:00Commented May 10, 2012 at 10:50
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@shiplu.mokadd.im: well, it's not a full duplicate: the said question only checks for the ending, but doesn't remove it. I'm vague about it.Vlad– Vlad2012-05-10 10:51:55 +00:00Commented May 10, 2012 at 10:51
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1"the script"? do you want an answer in some scripting language?PlasmaHH– PlasmaHH2012-05-10 10:53:43 +00:00Commented May 10, 2012 at 10:53
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There's like hundreds of different ways you can do this. Have you really not tried/found anything? Like here: en.cppreference.com/w/cpp/string/basic_stringjrok– jrok2012-05-10 11:38:25 +00:00Commented May 10, 2012 at 11:38
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6 Answers
How about:
// Check if the last three characters match the ext.
const std::string ext(".gz");
if ( s != ext &&
s.size() > ext.size() &&
s.substr(s.size() - ext.size()) == ".gz" )
{
// if so then strip them off
s = s.substr(0, s.size() - ext.size());
}
5 Comments
Aligus
substr() always creates new object. It's not sounds well by performance reasons.
Component 10
@Alexander: True, but there was no mention of performance considerations in the question.
MSalters
With very similar code, I managed to wipe 3 complete PCs(*). You probably want
s.size() > 3, as ".gz" is a hidden file and should not be stripped to "". ( * I stripped too much, added * and then did a rm -rf /* )Component 10
@MSalters: An impressive achievement! Tell me you didn't run it as root? :) I only really intended this as a simple example for the OP but I think your point is very important in context and I've changed accordingly. Thanks for sharing it!
Roland Illig
This code looks more complicated than necessary. Doesn't C++ have an
ends_with method like in Java or Python? And what is the point of s != ext? The code would work equally well without that comparison.If you're able to use C++11, you can use #include <regex> or if you're stuck with C++03 you can use Boost.Regex (or PCRE) to form a proper regular expression to break out the parts of a filename you want. Another approach is to use Boost.Filesystem for parsing paths properly.
1 Comment
Vlad
regex should be an overkill for such a simple task
Since C++17, you can use the built-in filesystem library to treat file paths, which is derived from the BOOST filesystem library. Note that the operator / has been overloaded to concatenate std::filesystem::paths.
#include <filesystem>
std::string stripExtension(const std::string &path_str) {
std::filesystem::path p{path_str};
if (p.extension() == ".gz") {
return p.parent_path() / p.stem();
}
return {};
}
Comments
void stripExtension(std::string &path)
{
int dot = path.rfind(".gz");
if (dot != std::string::npos)
{
path.resize(dot);
}
}
Comments
Or shorter version of another answer (C++11)
std::string stripExtension(const std::string &filePath) {
return {filePath, 0, filePath.rfind('.')};
}