Pass-by-Value vs. Pass-by-Reference in C++ Function Parameters

The article introduces two common parameter passing methods in C++: value passing and reference passing, with the core difference lying in their impact on the original variable. Value passing involves passing a copy of the actual parameter to the function, where the formal parameter is independent of the actual parameter. Modifying the formal parameter does not affect the original variable. For example, when swapping variables, the function modifies the copy, leaving the original variable's value unchanged. This is suitable for scenarios where the original data does not need modification or when the data volume is small. Reference passing transfers a reference (an alias of the variable) to the actual parameter, directly pointing to the original variable's address. Modifying the formal parameter will directly affect the actual parameter. Similarly, when swapping variables, the function modifies the original variable, resulting in the values being swapped. This is suitable for scenarios where the original data needs modification or when passing large objects (such as arrays or structures) to avoid copying overhead. Core differences: Value passing is "copying", while reference passing is "direct borrowing"; the former does not affect the original variable, and the latter does; the former uses ordinary types, and the latter uses reference types (`&`). When choosing, use value passing for read-only or small data, and reference passing for modification needs or large objects. Understanding this difference enables accurate variable manipulation.