Comparing C, C++, and Java

C, C++, and Java differ in language features and execution models.

Feature	C	C++	Java
`typedef`	O	O	X
`#define`	O	O	X
`goto`	O	O	Reserved but unavailable
Structures	O	O	X
Unions	O	O	X
Manual memory management	O	O	X
Operator overloading	X	O	X
Function or method overloading	X	O	O
Multiple class inheritance	X	O	X
Platform-independent bytecode	X	X	O

Main Function

C and C++ programs begin at a main function. Java applications use a main method in a class.

C++

#include <iostream>

int main(int argc, const char *argv[]) {
  std::cout << "Hello, World!\n";
  return 0;
}

Java

public class Main {
  public static void main(String[] args) {
    System.out.println("Hello world");
  }
}

In C and C++, main returns int and may omit its parameters. Java uses public static void main(String[] args).

C and C++ use a preprocessing step. A #define macro replaces tokens before compilation.

#define HELLO "Hello, World!\n"
#define MAX(a, b) ((a) > (b) ? (a) : (b))

Java has no equivalent preprocessor directive. Constants are commonly declared with static final.

public static final String HELLO = "Hello, World!\n";

Prefer language features such as constants, enums, and inline functions over macros where possible. Excessive macro use can make debugging difficult.