What does passing by value mean in C++?

Passing by value in C++ means that a copy of the variable is passed to a function. When a function takes parameters by value, it receives a duplicate of each argument's value. This means that any changes made to the parameter within the function do not affect the original variable used in the function call. The original variable remains unchanged because the function operates on the copy, not on the reference to the original data.

This approach is useful when you want to ensure that the original data is protected from modifications within the function. For example, if you were computing a result and did not want to alter any input variables, passing by value guarantees that the original data remains intact.

In contrast, passing a reference to the original variable would allow modifications to affect the original variable directly, which is not the case when using pass-by-value. As for passing multiple values at once, this typically involves passing other data structures like arrays or objects, which does not specifically address the concept of passing by value.