# Week 1 - Memory

## Team

Team name:
Date: 16-2-2022

Members

| Role | Name |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|
| **Facilitator** keeps track of time, assigns tasks and makes sure all the group members are heard and that decisions are agreed upon. |Max Huizing |
| **Spokesperson** communicates group’s questions and problems to the teacher and talks to other teams; presents the group’s findings. |Tim Eulink|
| **Reflector** observes and assesses the interactions and performance among team members. Provides positive feedback and intervenes with suggestions to improve groups’ processes. |Daan Roes|
| **Recorder** guides consensus building in the group by recording answers to questions. Collects important information and data. |Viggo te Woerd|

## Activities
Make sure to have the activities signed off regularly to ensure progress is tracked.

Set up a project in CLion to write the small programs needed in some of the activities.

### Activity 1: Memory usage - the *sizeof* operator

Data type Size in bytes:
char             1
short int        2
int              4
long int         4
long long int    8
float            4
double           8
long double      16
Pointer data type Size in bytes
char*            8
int*             8
float*           8
double*          8
void*            8

### Activity 2: Array and structure sizes
This is how you include code listings in your markdown document:

typedef struct {
	char name[80];
	int age;
} person_t;

void size_array(int array[]) {
	printf("Size of array parameter: %lu\n", sizeof(array));
}

void size_struct(person_t p) {
	printf("Size of p parameter: %lu\n", sizeof(p));
}

int main() {
	int array[10];
	person_t bob = {.name = "Bob", .age = 22};
	
	printf("Size of int array: %lu\n", sizeof(array));
	printf("Size of person_t structure: %lu\n", sizeof(bob));
	
	size_array(array);
	size_struct(bob);
}

Record your answer here

Size of int array: 40
Size of person_t structure: 84
Size of array parameter: 8
Size of p parameter: 84

### Activity 3: Memory addresses

int main( void )  {
	int a = 0xA0B0C0D0;
	short int b = 0x7856;
	const char * s = "Hello!";
	char buf[] = "Pointer";
	short int c = 0x3412;
	
	printf("int a: %p\n", (void*) &a);
	printf("short int b: %p\n", (void*) &b);
	printf("const char *s: %p\n", (void*) &s);
	printf("char buf[]: %p\n", (void*) buf);
	printf("short int c: %p\n", (void*) &c);
}	

Record your answer here
48 65 6c 6c 6f 21 00

### Activity 4: Observing automatic lifetime

Ja het geheugen wordt hergebruikt door de locale variabele.

### Activity 5: Observing the stack

Ja, het geheugen wordt hergebruikt in de add_poly functie.

### Activity 6: Leaking local addresses

De lokale stack van de functie wordt bewaardt todat iemand de ruimte nodig heeft uit de stack.

### Activity 7: Memory addresses of local variables

Nee dit werkt niet omdat de functie een adres van een lokale variable returnt.

### Activity 8: Using malloc

int* allocate_memory(int count){
    int *ptr = (int*) malloc(sizeof(int)*count);
}


int main(){
    int *longPtr;
    int *floatPtr;
    longPtr = (int*) malloc(sizeof(long));
    floatPtr = (int*) malloc(sizeof(float)*256);
    allocate_memory(20);

    return 0;
}

### Activity 9: Using allocated memory as an array

-
- Het programma kan dan een andere waarde pakken van een variabele.
- #include <stdio.h>

#include <malloc.h>

int main(void) {
    const int capacity = 20;
    int *ptr = (int *) malloc(capacity*sizeof (int));
    for (int i = 0; i < capacity; i++) {
        printf("ptr[%a] %d\n", i, ptr[i]);
    }
}

Er kunnen 20 ints worden opgeslagen

### Activity 10: Infinite memory?

Het programma crasht niet omdat de pointer na 122 keren null wordt.

### Activity 11: Fixing a memory leak

Record your answer here

### Activity 12: Dangerous `free`s

### Activity 13: Using realloc

Tien keer aangezien deze forloop tien keer runt.

### Activity 14: Using a dynamically sized buffer

Record your answer here


## Looking back

### What we've learnt

Dat je ruimte kunt reserveren en verwijderen.

### What were the surprises

Dat pointers in functies aan het eind van de fucntie worden weggegooid

### What problems we've encountered

We begrepen niet helemaal hoe malloc werkt.

### What was or still is unclear

Viggo zijn geaardheid

### How did the group perform?

Goed teamwork.