c++ number and string conversion

1 Use stringstream

   Add header file #include<sstream>

   number to string

   #include <string>

  #include <sstream>

  in t main(){
    double a = 123.32;
    string res;
    stringstream ss; define stream ss
    ss << a; convert number a to stream ss
    ss >> res; convert stream ss to string
    return 0;
  }

   String to Number

  #include <string>

  #include <sstream>

  int main(){
    double a = 123.32;
    string res;
    stringstream ss;  
    ss << a;                  
    ss >> res;
    return 0;
  }

//A method is wrapped here to convert a one-digit number into a two-digit string

//0->"00"    1->''01"

string transform(int num)
{
 string res;
 stringstream ss;
 ss<<num;
 ss>>res;
 if(num<10)
 {
  res="0"+res;
 }
 return res;
}