Format the precision and eliminate trailing zeros for 12 digits.

MString.cpp

@@ -86,7 +86,10 @@ namespace coreutils {
    }
 
    MString::MString(double value) {
-      std::string temp = std::format("{}", value);
+      std::string temp = std::format("{:.12f}", value);
+      temp.erase(temp.find_last_not_of('0') + 1, std::string::npos);
+      if (temp.back() == '.')
+	temp.pop_back();      
       setSize(temp.length());
       memcpy(this->data, (char *)temp.data(), temp.length());
       cursor = this->data;
@@ -133,7 +136,10 @@ namespace coreutils {
    }
 
    MString &MString::operator=(double value) {
-      std::string temp = std::format("{}", value);
+      std::string temp = std::format("{:.12f}", value);
+      temp.erase(temp.find_last_not_of('0') + 1, std::string::npos);
+      if (temp.back() == '.')
+	temp.pop_back();      
       setSize(temp.length());
       memcpy(this->data, (char *)temp.data(), temp.length());
       cursor = this->data;