Why Can't I Assign Temporary Objects to Non-Const References in C ?

Why Non-Const References to Temporary Objects Are Prohibited

C forbids assigning temporary objects to non-const references. This restriction stems from the fact that temporary objects vanish after the statement in which they are created. Allowing non-const references to temporary objects could lead to undefined behavior.

Consider the following code:

String& a = String("test"); // Error

This code attempts to assign a temporary String object to a non-const reference a. However, this is not allowed because a is not a const reference and temporary objects cannot be modified.

Some common reasons for this restriction include:

• Modifying temporary objects could lead to unpredictable results, as they are immediately destroyed after their statement ends.
• It would be difficult to determine when a temporary object has been modified, which could result in inconsistencies and errors.
• It could lead to increased complexity in the language, making it more difficult to understand and use.

C allows reading from temporary objects but not writing to them because reading does not alter the state of the object. However, writing to a temporary object could have unexpected consequences, as the object may be destroyed before the write operation completes.

Therefore, to prevent these potential problems, C restricts non-const references to temporary objects, while still allowing const references for safe reading purposes. This restriction helps ensure program correctness and prevents undefined behavior that could result from modifying temporary objects.

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