Does the sizeof Operator in C Evaluate at Compile Time or Run Time?

Does the Evaluation Time of sizeof Operator in C Depend on the Machine?

The sizeof operator in C calculates the size of a data type or variable, but does the result depend on the machine where the code is compiled or where the executable file is run?

Evaluation Time of sizeof

The answer to this question is no. Unlike some other operators, the evaluation of sizeof happens at compile time. This means that the compiler determines the size of the data type or variable when the program is compiled, not when it is executed.

For example, consider the following code snippet:

<code class="cpp">sizeof(short int)</code>

The result of this code snippet will be the same regardless of which machine compiles it or runs the executable. This is because the compiler will determine the size of the short int data type during compilation, which is typically 2 bytes. The executable file will simply carry this information, and the actual size of short int on the machine where the program is run will not affect the result.

Therefore, the evaluation time of the sizeof operator in C is determined at compile time, not at run time.

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