Regex

[nightmaregiba]

i want to find the position of the first string in input.txt that matches a regex

// Input.txt

[A-Z]o
Hello everyone, i am John
It is rainy today

// Here is my code

	string temp; // Store  "Hello everyone, i am John
                      //It is rainy today"
	temp.resize(500);
	char REGEX[500]; 
	FILE *fi;
	
	// Openfile-------------------------------------
	fi = fopen("input.txt","rt");
	if (fi == NULL)
	{
		cout << "Cant open file input.txt";
		return;
	}
	fscanf(fi,"%[^\n]\n",&REGEX);

	regex rg (REGEX); // regex ->>> string rg
	string regex = REGEX;

	// Store data to temp
	char s;
	int i = 0;
	int ntemp = 0; // temp elements number
	while (!feof(fi))
	{
		if (fscanf(fi,"%c",&s) > 0)
		temp[i] = s;
		i++;
		ntemp++;
	}
	temp[ntemp] = '\0';

	// Check
	string check = "";
	check.resize(500);
	for (int i = 0; i < ntemp - regex.length(); i++)
	{
		int pos ;
		for (int j = 0; j < regex.length() ; j++)
		{
			pos = j;
			check = check + temp[j];
		}
		if (regex_match(check,rg))
		{
			cout << pos;
			return;
		}
	}

[nightmaregiba]

Someone help!!!! It not run

[tmason]

Is this the complete code? What is the message?

If possible post complete code including what include files you are using, etc.

[nightmaregiba]

The only thing i need now is the code of finding the first string that matches the REGEX...

--->how to check a small string in the big one with REGEX???

example:

regex: "[A-Z]o"

and the string Big is "Hello everyone, I am John. It is rainy today"

code:

Compare "Bi" with the regex "[A-Z]o", then compare "ig" with the regex,... so on... THat!!! i need that

[cire]

#include <string>
#include <iostream>
#include <regex>

int main()
{
    std::string expression_text = "[A-Z]o";
    std::string text = "Hello everyone, i am John\nIt is rainy today";

    std::regex expr(expression_text);

    std::cout << "Regular expression: \"" << expression_text << "\"\n";
    std::cout << "Searchable text:\n\"" << text << "\"\n"; 

    const std::sregex_iterator beg(text.begin(), text.end(), expr), end;

    if (beg == end)
        std::cout << "No matches found.\n";
    else
        std::cout << "Matches:\n";

    for (auto it = beg; it != end; ++it)
        std::cout << '\t' << it->str() << '\n';
}

[nightmaregiba]

Thank you!!!!

it->position() <- we have the first position!!! great!!1