c++ Create a function whose inputs are 3 strings. Your function will return a string which is the concatenation of the three strings. (For example: the concatenation of the strings \"abc\", \"def\" and \"ghi\" is \"abcdefghi\".) 2.Create a function called round, which rounds a double to the nearest integer. The function returns this integer. 3.Create a function whose input is a string. Your function will create a new string from the old one by changing all lower case letters to upper case letters and vice versa. It leaves all other characters unchanged. Your function returns this string. Solution Ans 1) string Concat (string s1, string s2, string s3){ return s1+s2+s3;} Ans 2) int Round(double n){ return round(n); }Â Â //must include <math.h> Ans 3: string Change( string str){ for(int i=0;i<=strlen(str);i++) { if(str[i]>=97 && str[i]<=122) { str[i]=str[i]-32; } else if(str[i]>=65 && str[i]<=92) { str[i]=str[i]+32; } return str; } .