c++ - Why won't my do-while loop continue looping? -

i'm working on creating menu error checking , i've come with, can't seem work.

#include <iostream> using namespace std;  int main()  {  char option; // user's entered option saved in variable int error1 = 0;   //displaying options menu cout << "there 3 packages available." << endl; cout << "monthly price - price per mb overages (excluding c)" << endl; cout << "a) $15 - $.06 each mb after 200 mb." << endl; cout << "b) $25 - $.02 each mb after 2,000 mb ( approx. 2 gb)." << endl; cout << "c) $50 - unlimited data." << endl;  //do-while loop starts here {    //prompting user enter option according menu  cout << "please enter plan have : ";  cin >> option;  // taking option value input , saving in variable "option"   if(option == 'a' || option == 'a') // checking if user selected option 1  {     cout << "you chose a" << endl;     error1 = 1;  }  else if(option == 'b' || option == 'b') // checking if user selected option 2  {     cout << "you chose b" << endl;     error1 = 1;  }  else if(option == 'c' || option == 'c') // checking if user selected option 3  {     cout << "you chose c" << endl;     error1 = 1;  }  else //if user has entered invalid choice   {    //displaying error message    error1 = 0;    cout << "invalid option entered";  }  } while(error1 = 0);  //condition of do-while loop return 0; } 

when typing in incorrect value, output invalid option entered; however, won't loop beginning , prompt user input again.

why doing this?

change

while(error1 = 0);  //condition of do-while loop 

into this

while(error1 == 0);  //condition of do-while loop 

in first option assign 0 error1 , error1 being tested boolean means 0 false , non-0 true. sonce condition in while evaluated false, loop ends.