Extract cookies from an http header - c++

Question

I'm writing a C++ function that's going to extract cookies from an http header. The header is inside a string and it looks like this:
HTTP/1.1 200 OK
cache-control: no-cache, no-store, max-age=0, must-revalidate
content-language: en
content-length: 3202
content-type: text/html; charset=utf-8
date: Fri, 25 Apr 2014 13:31:44 GMT
etag: "46ec0cd3920851f7b63dbaa70280cd32"
expires: Mon, 01 Jan 1990 00:00:00 GMT
pragma: no-cache
server: tfe
set-cookie: d=32; path=/; expires=Sat, 25-Apr-2015 13:31:44 GMT
set-cookie: req_country=United+Kingdom; path=/; expires=Sun, 25-May-2014 13:31:44 GMT
I need this function to find the cookies:
set-cookie: d=32; path=/; expires=Sat, 25-Apr-2015 13:31:44 GMT
set-cookie: req_country=United+Kingdom; path=/; expires=Sun, 25-May-2014 13:31:44 GMT
and put them in to another string that's going to look lie this:
d=32; req_country=United+Kingdom;
There can also be more than 2 cookies in each header.
I've tried:
size_t p1 = header_data.find("set-cookie:");
size_t p2 = header_data.find(";");
std::string head = header_data.substr(p1,p2-p1);
and after execution it gave me the following error:
terminate called after throwing an instance of 'std::out_of_range'
what(): basic_string::substr
Aborted (core dumped)

Answer 1

Try this code. Not optimized, but i guess it works in way you want:
#include <iostream>
#include <vector>
#include <sstream>
using namespace std;
std::vector<std::string> &split(const std::string &s, char delim, std::vector<std::string> &elems) {
std::stringstream ss(s);
std::string item;
while (std::getline(ss, item, delim)) {
elems.push_back(item);
}
return elems;
}
std::vector<std::string> split(const std::string &s, char delim) {
std::vector<std::string> elems;
split(s, delim, elems);
return elems;
}
int main() {
std::string header =
"HTTP/1.1 200 OK\n"
"cache-control: no-cache, no-store, max-age=0, must-revalidate\n"
"content-language: en\n"
"content-length: 3202\n"
"content-type: text/html; charset=utf-8\n"
"date: Fri, 25 Apr 2014 13:31:44 GMT\n"
"etag: \"46ec0cd3920851f7b63dbaa70280cd32\"\n"
"expires: Mon, 01 Jan 1990 00:00:00 GMT\n"
"pragma: no-cache\n"
"server: tfe\n"
"set-cookie: d=32; path=/; expires=Sat, 25-Apr-2015 13:31:44 GMT\n"
"set-cookie: req_country=United+Kingdom; path=/; expires=Sun, 25-May-2014 13:31:44 GMT\";\n";
vector<string> headerLines = split(header, '\n');
for (int i(0); i != headerLines.size(); ++i) {
if (headerLines[i].find("set-cookie:") != std::string::npos) {
std::string variablesPart = split(split(headerLines[i], ';')[0], ':')[1];
std::cout << "\nExtracted: {" << variablesPart << "}";
}
}
}