C vs. Java

Note these 2 samples of code:

Java:

class HelloWorld {
	public static void main(String[] args) {
	System.out.println("Hello, world!");
		for (int i = 0; i < args.length; i++) {
			System.out.printf("%d: %s\n", i, args[i]);
		}
	}
}

C:

#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[]) {
 
	fprintf(stdout, "Hello, world!\n");
		for(int i = 0; i < argc; i++) {
			printf("%d: %s\n", i, argv[i]);
		}
 
	return EXIT_SUCCESS;
}

Both do the same thing effectively, but note the differences. Java’s io is built into the language and doesn’t require imports. Everything is also made its own class. C is procedural, and lacks the ability to make objects.

The *argv[] in C represents an array of pointers to characters, which are effectively strings that are terminated by the NUL character.

Encapsulation

C:

• Uses Procedures and structs

Java:

• Uses objects, classes, and interfaces

References

C:

• Makes pointers explicit (denoted by * or &)

Java:

• Abstract object references automatically managed by the compiler/language

Strings

C:

• Uses a null-terminated array of chars (where null is denoted as \0)

Java:

• Uses a built in java.lang.String class
• Strings represent objects

Parameters

C:

• Always is pass by value
• For this reason, pointers have to be explicitly entered

Java:

• Passes the value of the reference of an object
• Essentially only passes the value if it is primitive, reference if it is an object

Memory Management/Allocation

C:

• Memory must be manually allocated, using malloc

Java:

• Allocates memory for objects when created using new
• Memory is cleared using the JVM Garbage Collector

”Objects”

C refers to variables as “objects,” and they are used interchangeably. Note that it is purely just a reference in memory in C.

Compilation and Running

In Java, you use the JVM, it makes it easy to run code on any machine.

In C, you’ll be using the C Toolchain. Code must be compiled for each machine.