91Ó°ÊÓ

In passing by value, a copy of the variable is created, and the function works with this copy. Any changes made to the variable within the function do not affect the original variable outside the function.

In passing by reference, a reference (address) to the memory location of the original variable is passed to the function. Any changes made to the variable within the function directly modify the original variable outside the function.

Let's consider a simple example in which we have two variables `x` and `y`, with values 5 and 7 respectively. We want to swap their values using a function. Passing by value: ```c void swap_by_value(int a, int b) { int temp = a; a = b; b = temp; } ``` When you call `swap_by_value(x, y);`, the values of the variables `x` and `y` are not changed, because the function works with a copy of the variables. The values of `a` and `b` are only changed within the function's scope. Passing by reference: ```c void swap_by_reference(int* a, int* b) { int temp = *a; *a = *b; *b = temp; } ``` When you call `swap_by_reference(&x, &y);`, the memory addresses of the variables `x` and `y` are passed into the function, and their values are swapped. The changes made to the pointers `a` and `b` are reflected in the original variables, so the values of `x` and `y` are effectively swapped.

In summary, passing by value creates a copy of the original variable and does not affect the original variable, while passing by reference directly works with the memory location of the original variable, allowing changes to be reflected in the original variable.