How can I convert String into int and int into string in C++ and Java??

In Java you should use valueOf method for both conversions:

https://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#valueOf(java.lang.String)

https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#valueOf(int)

So to convert int to String you write:

int number = 1;
String stringFromNumber = String.valueOf(number);
// shorthand will be
String stringFromNumber = number + "";

To convert int to String is harder, because you have to account for NumberFormatException, see Docs links above:

String numberString = "1";
int intFromString;
try {
  intFromString = Integer.valueOf(numberString);
} catch (NumberFormatException nfe) {
   // do something
   System.out.println(numberString + " is not a number");
}  

For C++ I don't know, so you have to google yourself...

For C++, you would use a function called itoa and stoi. These stand for integer to http://www.cplusplus.com/reference/cstdlib/itoa/ http://www.cplusplus.com/reference/string/stoi/

To convert from an int to a string, you would type out:

int a = 10; char *intStr = itoa(a); string str = string(intStr);

To convert from string to an int you would use stoi: http://www.cplusplus.com/reference/string/stoi/

string str1 = "45"; int myint1 = stoi(str1);

Sorry for the late response, but hey, maybe it'll help someone else down the line.