2D Arrays

Week 5 Lab Exam

This course has an invigilated final exam
To prepare you on the format, we are having a week 5 in-lab exam
Please attend your week 5 lab as scheduled
Worth 1 mark

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Strings recap

An array of chars
We have a single identifier for the string
Anything we can do with arrays, applies

`char[]`

Notice the \0 at the end! This means that C will know when it reaches the end of the array

Note the # of elements, and don't forget the \0

String literals

`"Jake!"`

uses double quotes " to wrap the string literal
single quote for characters!
Used to assign strings to char[] easily:
char name[] = "Jake Renzella";

Useful string functions

fgets() -> reads a string
fputs() -> prints a string
strlen() -> gives us the length of the string (excluding the \0).
strcpy() -> copy the contents of one string to another
strcat() -> join one string to the end of another (concatenate)
strcmp() -> compare two strings
strchr() -> find the first occurrence of a character
note: some of these may require #include <string.h>

Reassigning a string

int main(void) {
    char name[MAX_LEN] = "Jake";
    strcpy(name, "Mr Otterington");
}

^ Remember we can't reassign like:

name = "Mr Otterington";

Arrays of Structs

Concept Introduction

Structs

Structs allow us to store groupings of data
We define structs above main and specify each field's type
We use the . operator to access the field once we initialise a struct!

Arrays

We can create arrays to store multiples of data
They are homogenous, so can only store the same type

We can have arrays of type (char, int, struct, enum)

Structs 🤝 Arrays?

Yes!

Array of structs

Use students[1].name; to access element 1's name

2D arrays

Array of arrays

2D arrays

<type> <identifier>[<rows>][<cols>];

int my_grid[5][5];
my_grid[2][3];

Visualisation

Large demo Program

An array of array of structs
Battleships? Naughts and Crosses?

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