Test MDX File V3

This is a Test MDX File for my Code Gap Check setup. Test callout:

The Evolution and Core Principles of C++

C++ is a powerful, object-oriented programming language that has played a significant role in software development since its inception. Developed by Bjarne Stroustrup at Bell Labs (now AT&T Labs) between 1983 and 1985, C++ built upon the foundations of the C language. C itself has a rich lineage, tracing back to the B language (1970) by Ken Thompson and ultimately to the BCPL language.

Knowledge Check

Concept Match

Match C++ Memory Concepts

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Drag each definition into its matching concept slot, then click Submit. Tap × to return a placed card to the pool.

Stack

drag a definition here…

Heap

drag a definition here…

volatile

drag a definition here…

const

drag a definition here…

Definition Pool

Manually managed region used for dynamic allocation via new/delete.

Prevents the compiler optimising reads of a hardware-modified variable.

Marks a variable as read-only after initialisation.

Automatically managed memory for locals; freed on scope exit.

Submit

Here is an example of a Code Order exercise (C++), expanded by default …

Code Order

C++

Arrange a Hello World Program

Drag the tiles to arrange the code in the correct order, then click Submit. Locked lines stay in place.

return 0;

int main() {

#include <iostream>

cout << "Hello world!\n";

using namespace std;

}

Submit Order

Here is a Code Order exercise (Rust), collapsed by default … The opening fn main() { and the closing } are locked — the puzzle is really about assembling the iterator chain in the right order.

Code Order

Rust

Build a Rust Iterator Chain

Interactive Memory Lab

The lab below is pre-loaded with the textbook example: float a = 25.0;, int b = 545;, and double c = 123.0;. Drag any type from the palette onto the memory strip to allocate it. Click a placed variable to rename it or change its value.

C++ Memory Lab

Drag a type onto memory and watch the variable claim the bytes its size demands.

derekmolloy.ie

Memorybase = 0x1000

16 / 16 bytes used0 free

+0

+4

+8

+C

×

a

25.0

×

b

545

×

c

123.0

byte 0

4

8

12

Type Palette — drag onto memory

Textbook exampleClear memory

bool8-bit

char8-bit

short16-bit

int32-bit

unsigned int32-bit

long64-bit

unsigned long64-bit

float32-bit

double64-bit

integer types

floating point

character

boolean

Declared variables

Type	Name	Value	Address	Size
float	a	25.0	0x1000 – 0x1003	4 bytes (32-bit)
int	b	545	0x1004 – 0x1007	4 bytes (32-bit)
double	c	123.0	0x1008 – 0x100F	8 bytes (64-bit)

Try this:Click Textbook example to load a, b, c. Then drag a char onto memory — notice it claims a single byte, same as a bool, while double claims eight. Click any placed variable to rename it or change its value. With 16 bytes of memory there's no room for all five textbook variables at once — that's the point: char and bool are cheap, double is expensive.

A Narrower View

Same lab, but with a smaller memory region (8 bytes) and a different base address — useful when showing how a single double fills the entire visible region.

Tight Memory (8 bytes)

Drag a type onto memory and watch the variable claim the bytes its size demands.

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