How to swap in string function in c++ language?

[candie3]

i wanted to swap between to variables in ma string fuction, used [swap(sting1,string2)];
but i failed an error ocured that that swap was not a reserved word in string functions, so i just wanted to konw how i can do this.

[kokosek]

http://www.cplusplus.com/reference/string/swap
If You want more help, I will need the code and the error.