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Microsoft visual c++ 2010 express how to i fix - Error: identifier "cout" is undefined?

• i have recently started programing using microsoft visual c++ 2010 express and the error "Error: identifier "cout" is undefined" keeps coming up when ever i type cout or cin . also it worked before when i made a simple calculator but it wont work now here is the code : // project1.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <vector> #include <string> using namespace std; int main () { double num1 , num2 , result,; int choose; cout << " enter number 1"; cin >> num1; cout << "enter number 2"; cin >> num2; cout << "1. add 2.subtract 3.divide 4.multiply: "; cin >> choose; if (choose == 1) result = num1 + num2; else if (choose == 2) result = num1 - num2; else if (choose == 3) result = num1 / num2; else if (choose ==4) result == num1 * num2; cout << "your result is: " << result << endl; return 0; }

• Answer:

  Add #include <iostream> a the beginning and it should fix it.