add std::string to number funtion

include/toolkit.h

@@ -3,6 +3,8 @@
 
 #include <charconv>
 #include <expected>
+#include <type_traits>
+#include <string_view>
 
 //use for to_chars
 constexpr size_t buffer_size = 32;
@@ -18,6 +20,18 @@ namespace toolkit{
         }
         return std::string(buffer, res.ptr - buffer);
     }
+    
+    template<typename T = double>// requires std::is_same_v<T, std::string>
+    std::expected<T, std::string> stoi(const std::string& str){
+        T value;
+        
+        auto res = std::from_chars(str.c_str(), str.c_str() + str.size(), value);
+        if(res.ec != std::errc()){
+            return std::unexpected(std::make_error_code(res.ec).message());
+        }
+        return value;
+        
+    }
 }
 
 #endif