C/C++ :: String Not Being Declared

I'm setting the Arduino to send data from it's analog pins through to my PC, but to keep it easier to manage, I'm trying to turn the analog reading into a character string, so instead of sending just the value, it instead sends "Pin 1: 345" for example, where 1 is the number of the analog pin in use, and 345 is the reading from that pin.

In my code below, the problem is getting my string variable to be recognized. When I try to verify the code, the error message I get reads "'string' does not name a type" yet when I compare it to other string variable examples on the internet, I can see no difference between mine and the ones online.

I've tried having the declaration in the loop, outside of the loop, and now at the start with the other declarations.

#include <string>
using namespace std;
string outText;
void setup() {
Serial.begin(9600);

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