I wrote a function:

Qt Code: 
  1. #include<qstring.h>
  2.  
  3. void Calculator::calculation(QString &operation, QString &text_display)
  4. {
  5. 	QString a_string = "", b_string = "", result_string = "";
  6. 	double a, b, result;
  7. 	int position = 0, i, j;
  8.  
  9. 	while(1)
  10. 	{
  11. 		if ( ( position = operation.find('*') ) == -1 ) break;
  12.  
  13. 		for( i = position; i = 0 ; i-- )
  14. 		{
  15. 			if( operation.at( i ) == '*' || operation.at( i ) == '/' || operation.at( i ) == '+' || operation.at( i ) == '-' )
  16. 				break;
  17. 			a_string += operation.at( i );
  18. 		}
  19. 		for( j = position; j < operation.length() ; j++ )
  20. 		{
  21. 			if( operation.at( j ) == '*' || operation.at( j ) == '/' || operation.at( j ) == '+' || operation.at( j ) == '-' )
  22. 				break;
  23. 			b_string += operation.at( j );
  24. 		}
  25. 		a = a_string.toDouble();
  26. 		b = b_string.toDouble();
  27. 		result = a*b;
  28. 		result_string = result_string.setNum( result, 'f', 10 );
  29. 		operation.replace( i, i + j + 1, result_string );
  30. 	}
  31. 	text_display = result_string;
  32. 	ui.display->setText( text_display );
  33. }
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Compiler says that QString class has no member function called 'find' (line 11), but when I read QString documentation...

http://doc.trolltech.com/3.3/qstring.html#find

...it's right there. Every other function like lenght() or at() works. What's wrong then?