Write C++ statements to perform the following string operations

String Operation	C++ Statement
Declare string1 and string2 to initialize your first name and last name
Make a string3 after concatenate string1 and string2
Update the string3 by inserting a single space between first name and last name using build in function
Calculate and show the total length of string3
Replace a single space between first name and last name with underscore using build in function