Structure parameters are passed-by-value

Passing objects as parameters in Java and in C

C and Java exhibit the same difference in behavior describe in this webpage, when you pass (= copy !!) an object as parameter to a function:

In Java, the program passes (= copies) a reference (= address)
Result:
In C, the program passes (= copies) an entire object
Result:

Here are 2 programs to show you this fact:

struct_param.java	struct-param.c
class BankAccount { int accNum; double balance; }; public class struct_param { public static void f( BankAccount x ) { x.accNum = 888; x.balance = 9999.0; } public static void main(String[] argv) { BankAccount a; a = new BankAccount( ); // Create the objects a.accNum = 123; a.balance = 1000.0; System.out.printf("a = (%d, %f)\n", a.accNum, a.balance); f(a); // Pass a /* =================================================== Proof that objects in Java are passed by reference =================================================== */ System.out.printf("a = (%d, %f)\n", a.accNum, a.balance); } }	#include <stdio.h> struct BankAccount { int accNum; double balance; }; void f( struct BankAccount x ) { x.accNum = 888; x.balance = 9999.0; } int main(int argc, char argv[]) { struct BankAccount a; a.accNum = 123; a.balance = 1000.0; printf("a = (%d, %f)\n", a.accNum, a.balance); f(a); // Pass a / =================================================== Proof that objects in C are passed by value =================================================== */ printf("a = (%d, %f)\n", a.accNum, a.balance); }

struct_param.java

struct-param.c

class BankAccount { int accNum; double balance; }; public class struct_param { public static void f( BankAccount x ) { x.accNum = 888; x.balance = 9999.0; } public static void main(String[] argv) { BankAccount a; a = new BankAccount( ); // Create the objects a.accNum = 123; a.balance = 1000.0; System.out.printf("a = (%d, %f)\n", a.accNum, a.balance); f(a); // Pass a /* =================================================== Proof that objects in Java are passed by reference =================================================== */ System.out.printf("a = (%d, %f)\n", a.accNum, a.balance); } }

#include <stdio.h> struct BankAccount { int accNum; double balance; }; void f( struct BankAccount x ) { x.accNum = 888; x.balance = 9999.0; } int main(int argc, char *argv[]) { struct BankAccount a; a.accNum = 123; a.balance = 1000.0; printf("a = (%d, %f)\n", a.accNum, a.balance); f(a); // Pass a /* =================================================== Proof that objects in C are passed by value =================================================== */ printf("a = (%d, %f)\n", a.accNum, a.balance); }

Output of the Java program:

cs255-1@aruba (5681)> java struct_param a = (123, 1000.000000) a = (888, 9999.000000)

Output of the C program:

cs255-1@aruba (5681)> java struct_param a = (123, 1000.000000) a = (123, 1000.000000)

Example Program: (Demo above code)
- Prog file: /home/cs255001/demo/C/set2/struct_param.java + struct-param.c
How to run the program: