In programming, the concepts of "pass by reference" and "pass by value" refer to different methods of passing arguments to functions, which can affect how function calls manipulate data and manage memory.
Pass by Value
When arguments are passed by value, a copy of the data is made and passed to the function. This means that any modifications to the arguments within the function do not affect the original data in the calling function. Each modification is made to the copy, and once the function execution is complete, the changes are discarded along with the copy of the data. This method is generally safer as it prevents unintended side effects from affecting the original data. However, it can be less efficient, especially with large data structures, because it requires copying all the data being passed[1][2][3][6][10][11][12].
For example, in C++ and Java, primitive data types (like int, char) are passed by value by default. This means that functions receive a copy of the arguments, not the actual data stored in the variables[2][4].
Pass by Reference
Pass by reference, on the other hand, involves passing the address (or a reference) of the data rather than a copy of the data itself. This means that the function operates directly on the original data, and any changes made within the function are reflected in the original variables passed. This can be more efficient, as no copying of data is required, but it also increases the risk of side effects, as the function can alter the state of the variables used to call it[1][2][3][6][7][13][14].
In languages like C++, you can explicitly pass a variable by reference using the & operator in the function declaration. Similarly, in languages that support pointers, such as C and C++, passing by reference can be achieved by passing pointers to the variables (using the * and & operators)[7][8].
