Is there a more efficient way to extract the file name of a file?-CodePudding

The code bellow extracts the file name of a file using its path.

#include <iostream>
#include <vector>

using namespace std;

int main() {
    cout << "Program operating..." << endl;

    string s = "C:\\Users\\user\\Pictures\\Strategic_Offense_Logo_1";
    string name;
    for (unsigned int i = s.size() - 1; i > 0; i--) {
        if (s[i] == '\\') {
            for (unsigned int j = i   1; j < s.size(); j  ) {
                if (s[j] == '.' || j == s.size() - 1) {
                    if (j == s.size() - 1)
                        j  ;
                    vector<char> v(j - i - 1);
                    unsigned int l = 0;
                    for (unsigned int k = i   1; k < j; k  ) {
                        v[l  ] = s[k];
                    }
                    char* vectorAsArray = &v[0];
                    name = vectorAsArray;
                    name.resize(v.size());
                    break;
                }
            }
            break;
        }
    }
    cout << name << endl;
}

#include <iostream>
#include <vector>

using namespace std;

int main() {
    cout << "Program operating..." << endl;

    string s = "C:\\Users\\user\\Pictures\\Strategic_Offense_Logo_1.png";
    string name;
    for (unsigned int i = s.size() - 1; i > 0; i--) {
        if (s[i] == '\\') {
            for (unsigned int j = i   1; j < s.size(); j  ) {
                if (s[j] == '.' || j == s.size() - 1) {
                    if (j == s.size() - 1)
                        j  ;
                    vector<char> v(j - i - 1);
                    unsigned int l = 0;
                    for (unsigned int k = i   1; k < j; k  ) {
                        v[l  ] = s[k];
                    }
                    char* vectorAsArray = &v[0];
                    name = vectorAsArray;
                    name.resize(v.size());
                    break;
                }
            }
            break;
        }
    }
    cout << name << endl;
}

Is there a more efficient way to do this?

Purpose: I am making a texture class and I want to refer the texture by its name instead of its path or a made up ID.

Note: library does not work at all with the visual studio compiler. If you know how to fix it or have an alternative solution, please post.

CodePudding user response：

Use std::filesystem::path::filename.

That said, you should refer to the texture by its fully qualified path or a unique ID; otherwise, you will get collisions for textures with the same name in different folders.

CodePudding user response：

The simplest solution is to use the <filesystem> library in C 17 onward, specifically the std::filesystem::path class and its stem() method:

Returns the filename identified by the generic-format path stripped of its extension.

#include <iostream>
#include <filesystem>

namespace fs = std::filesystem;
using namespace std;

int main() {
    cout << "Program operating..." << endl;

    //fs::path p = "C:" / "Users" / "user" / "Pictures" / "Strategic_Offense_Logo_1.png";
    fs::path p = "C:\\Users\\user\\Pictures\\Strategic_Offense_Logo_1.png";
    fs::path name = p.stem();

    cout << name << endl;
}

However, if that is not an option, there is a simple solution using the available methods of std::string, such as rfind() and substr():

#include <iostream>
#include <string>

using namespace std;

int main() {
    cout << "Program operating..." << endl;

    string s = "C:\\Users\\user\\Pictures\\Strategic_Offense_Logo_1.png";

    string name = s.substr(s.rfind('\\') /* or: s.find_last_of("\\/") */   1);
    name.resize(name.rfind('.'));

    cout << name << endl;
}

CodePudding user response：

Visual Studio defaults to C 14. To be able to access <filesystem> and all of its features (like extracting file names), one has to go into the solution properties under C and change the version to the latest. Then, and only then, <filesystem> will work, as everyone in the Internet and StackOverflow talks about.