In mixed expressions, what occurs with different data types?

In mixed expressions involving different data types, the values are converted to a single data type to provide a consistent type for the operation being performed. This process is known as "type promotion" or "implicit conversion."

For example, if you combine an integer and a floating-point number in an expression, the integer will be converted to a float so that both operands match in type, allowing the operation to be executed without error. This conversion ensures that calculations can proceed smoothly without the programmer needing to manually adjust the data types.

The other options are not applicable in this context. For instance, while runtime errors can occur in some cases, they are not a direct outcome of mixed data types since C++ manages type conversions. The idea that mixed types cannot be executed is incorrect, as C++ allows for expressions involving multiple data types through this conversion mechanism. Lastly, saying that mixed types are ignored in calculations is inaccurate because C++ computes the result by converting the operands to a common type, rather than overlooking any component of the expression.