Hey Jane, let's break down that no viable overloaded '=' error you're seeing—this is a super common issue in C++ (my best guess is that's the language you're working with here!) and it usually boils down to one of a few key problems. Here are the most likely culprits:

• You're trying to assign to a non-modifiable object
  If the variable you're assigning to is marked const, or belongs to a class that has const members, reference members, or a base class that disables assignment, the compiler will block the assignment. For example:

  const int fixed_val = 42;
  fixed_val = 50; // Error: Can't assign to a const variable
  
  class ReadOnlyClass {
      const int id;
  public:
      ReadOnlyClass(int i) : id(i) {}
  };
  
  ReadOnlyClass obj1(1), obj2(2);
  obj1 = obj2; // Error: Default assignment operator is deleted because of the const member
  

• Mismatched types with no valid assignment operator
  This happens when you're trying to assign a value of one type to a variable of another, and there's no built-in conversion or custom overloaded operator= to handle it. For example:

  std::string my_str;
  my_str = 123; // Error: No assignment operator for int → std::string
  
  class Car {};
  class Bike {};
  
  Car my_car;
  Bike my_bike;
  my_car = my_bike; // Error: No overloaded operator= to assign Bike to Car
  

• Assigning to a temporary/rvalue object
  Sometimes you might accidentally try to assign a value to a temporary object (like the result of a function call that returns an rvalue) instead of a persistent, modifiable variable. For example:

  // Error: Can't assign to a temporary std::string rvalue
  std::string("hello") = "goodbye";
  

If you can share the specific code snippet that's triggering this error—especially the line with the assignment and any relevant class/type definitions—I can zero in on exactly what's going wrong here!

内容的提问来源于stack exchange，提问作者Jane