正则表达式未声明（Dev C ++）

Question

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <regex.h>

using namespace std;

string input;

int main()
{   
    //Input .ply file
    ifstream inputFile ("input.ply");


    //input file is read
    if (inputFile.is_open())
    {
        int i = 1;  //Line iterator
        int vertices = 0;
        int faces = 0;

        vector<float> anatomy;
        vector<float> normals;
        vector<int> triangles;

        string a,line;
        getline(cin,line);

        while (inputFile.good())
        {
            //Take number from line 4, set as variable "vertices"
            if (i == 4)
            {
                regex pattern("[^0-9]+");
                getline (inputFile,line);              
                vertices = show_match(line, pattern);
            }

            //Take number from line 11, set as variable "triangles"
            if (i == 11)
            {
                regex pattern("[^0-9]+");
                getline (inputFile,line);              
                faces = show_match(line, pattern);
            }

            if (i == 13)
            {
                i++;
                break;
            }

            i++;

        }

        waitKey(0);
}

else
{
    cout << "Cannot read mesh, please try again." << endl;
}

return 0;

}

Just trying to read from a string and extract the integer, so I have added the regex header and other files in order to use regular expressions. I'm using Dev-C++ and have extracted the files for regex into their respective lib , bin and include folders in " C:\\Dev-Cpp ", but I am still receiving the following error when I attempt to compile my program:

'regex' undeclared (first use this function)

Answer 1

You will get this error msg from the compiler if your statement #include <regex.h> is not reached, for example if you used conditional includes.

Make sure that #include <regex.h> is actually reached. I got this error message too when I accidentally excluded the include by using a conditional include for linux and then trying the code with openbsd .