Calling a function in CPP and passing values to that function can be done in two ways:
- Call by Value
- Call by Reference
| Call by Value | Call by Reference |
| Original value of the function parameter is not modified. | Original value of the function parameter is modified. |
| In this method, we pass a copy of the value to the function. | In this method, we pass an address of the value to the function. |
| The value to be passed to the function is locally stored. | The value to be passed to the function is stored at the location same as the address passed. |
| The value changed inside the function, changes for the current function only. | The value changed inside the function, changes for both inside as well as outside the function. |
| Actual and Formal arguments have unique address spaces. | Actual and Formal arguments shares the same address space. |
Example 1: Example for CPP Call by Value
#include <iostream.h> using namespace std; int sum(int a, int b) { int c; c = a+b; return c; } int main() { int x = 100; int y = 200; int add; add = sum(x,y); cout << x <<" + " << y << " = " << add; return 0; } |
Output
100 + 200 = 300 |
Example 2: Example for CPP Call by Reference.
#include <iostream.h> using namespace std; int sum(int *a, int *b) { int *c; *c = *a + *b; return *c; } int main() { int x = 100; int y = 200; int add; add = sum(&x,&y); cout << x <<" + " << y << " = " << add; return 0; } |
Output
100 + 200 = 300 |
