c++ url decoder

main.cpp

#include <iostream>
#include <stdlib.h>
#include <string>

std::string url_decode(char *url) {
	std::string temp, output;
	char ch;
	for (unsigned int index = 0; index < strlen(url)+1; index++) {
		if (url[index] == '%') {
			temp += url[index+1];
			temp += url[index+2];
			ch = std::stoul(temp, nullptr, 16);
			output += ch;
			temp = "";
			index+=2;
		} else if (url[index] == '+') {
			output += " ";
		} else {
			output += url[index];
		}
		
	}
	return output;
}

int main() {
	char url[] = "hello%40%23%24_%26-%2B()%2F*%22%27%3A%3B!%3F%2C.~%60%7C%E2%80%A2%E2%88%9A%CF%80%C3%B7%C3%97%C2%B6%E2%88%86%C2%A3%C2%A2%E2%82%AC%C2%A5%5E%C2%B0%3D%7B%7D%5C%25%C2%A9%C2%AE%E2%84%A2%E2%9C%93%5B%5D%3C%3E%20++%5Bweeks";
	std::cout << url_decode(url) << "\n";
	return 0;
}

Compile:

g++ main.cpp -o $HOME/main

Output:
./main
hello@#$_&-+()/*"':;!?,.~`|•√π÷׶∆£¢€¥^°={}%©®™✓[]<> [weeks