add split string function

bin/main.cpp

@@ -1,6 +1,11 @@
-#include "src/string/string.hpp"
+#include <iostream>
+
+#include "string/string.hpp"
 
 int main(int argc, char *argv[])
 {
-  return 0;
+  std::string str { "asdf,qwer,zxcv" };
+  hack::v_str v = hack::split_str(str, ',');
+
+  for (const auto& c : v) std::cout << c << std::endl;
 }