How can i create a command to use it in input in c++

Question

For example I want to create a command name 'start_day' , and when user use it in input every string user type next will be save in that day

// start_day 13/9/2020
// Today was boaring

In the example above "today was boaring will be save in 13 / 9 / 2020

*Thanks*

Answer 1

void start_day(unordered_map<string,string>&m)
{
string date,data;
cin>>date;
getline(cin,data);
m[date] = data;
}
By interpreting your example I came up with this, I hope this helps you.