Call by value

Call by value

In call by value (or pass by value), the evaluated value of the argument expression is bound to the corresponding variable in the function (frequently by copying the value into a new memory region). If the function or procedure is able to assign values to its parameters, only its local variable is assigned—that is, anything passed into a function call is unchanged in the caller's scope when the function returns. For example, in Pascal, passing an array by value will cause the entire array to be copied, and any mutations to this array will be invisible to the caller: