Programming Fundamentals

Check in week

Reminder: This week is a check-in week, so please make sure to stay around in the lab time for your one-on-one with one of your Tutors.

Part 1: 2D Arrays Practice (20 min max)

In this section we will write a short program that deals with 2D arrays.

This program is the starting point we'll be using today:

#include <stdio.h>

#define SIZE 5

// Function Prototype
int did_player_win(char player, char board[SIZE][SIZE]);

int main(void) {
    char no_wins_board[SIZE][SIZE] = {
        {'O', 'X', ' ', ' ', 'X'},
        {' ', 'X', ' ', ' ', ' '},
        {' ', 'X', 'O', ' ', ' '},
        {'O', 'X', 'O', 'O', 'O'},
        {'X', ' ', ' ', ' ', 'O'},
    };

    char x_wins_board[SIZE][SIZE] = {
        {'O', 'X', ' ', ' ', 'X'},
        {' ', 'X', ' ', ' ', ' '},
        {' ', 'X', 'O', ' ', ' '},
        {'O', 'X', 'O', 'O', 'O'},
        {' ', 'X', ' ', ' ', 'O'},
    };
    char o_wins_board[SIZE][SIZE] = {
        {'O', 'X', ' ', ' ', 'X'},
        {' ', 'X', ' ', ' ', ' '},
        {' ', 'X', 'O', ' ', ' '},
        {'O', 'O', 'O', 'O', 'O'},
        {'X', 'X', ' ', ' ', 'O'},
    };

    if (did_player_win('X', no_wins_board)) {
        printf("X Won This Board!\n");
    } else if (did_player_win('O', no_wins_board)) {
        printf("O Won This Board!\n");
    } else {
        printf("Nobody has won this board!\n");
    }
}

// Function Implementation:
// Determines whether a given player has won the game of tictactoe
// by getting SIZE tokens in a row, in any direction.
int did_player_win(char player, char board[SIZE][SIZE]) {
    // TODO Implement this function.
    return 0;
}

It is simple tic-tac-toe game; with the code to check who won left empty. You should check whether any rows, columns, or diagonals are all claimed by the same person. If someone has SIZE-in-a-row, you should return 1 to indicate that the player won. Otherwise, return 0.

A few boards have been provided as examples.

Part 2: Arrays and Functions (20 min max)

In this section, we'll practice writing and using functions, focusing in particular on how they interact with arrays.

During this activity, you will implement the following functions:

  1. Write the following function: void square(int x);, which
    • Takes in an integer x
    • Modifies x so that it equals x * x.
  1. Write a function called square_array, which
    • Takes in array (called array) of size length.
    • Squares all elements inside the array.

Part 3: Strings (20 min max)

Warmup:

Your tutor may briefly run through the following code with you:

#include <stdio.h>

// Manually prints out a string, one character at a time.
// Should behave like printf("%s\n");
void print_string(char *string) {
    int i = 0;
    while (string[i] != '\0') {
        printf("%c", string[i]);
        i++;
    }
    printf("\n");
}

int main (void) {
    char my_string[] =  "Many chars";

    print_string(my_string);
    return 0;
}

Practice

In this section you'll be completing some string activities in your groups.

Have a quick look at the following char functions that have been implemented for you:

// Provided char functions

// Returns : 1 if `c` is a lowercase letter
//         : 0 otherwise.
int is_lowercase(char c) {

    return 'a' <= c && c <= 'z';
}

// Returns : 1 if `c` is an uppercase letter
//         : 0 otherwise.
int is_uppercase(char c) {

    return 'A' <= c && c <= 'Z';
}

// Returns : 1 if `c` is a letter
//         : 0 otherwise.
int is_letter(char c) {

    return is_lowercase(c) || is_uppercase(c);
}

// Returns : `c` converted to lowercase, if it was an uppercase letter
//         : `c` unmodified, otherwise
char to_lowercase(char c) {
    if (is_uppercase(c)) {
        return c - 'A' + 'a';
    }

    return c;
}

// Returns : `c` converted to uppercase, if it was a lowercase letter
//         : `c` unmodified, otherwise
char to_uppercase(char c) {
    if (is_lowercase(c)) {
        return c - 'a' + 'A';
    }

    return c;
}

// Returns : 1 if `c` is an uppercase or lowercase vowel
//         : 0 otherwise.
int is_vowel(char c) {
    char lower_c = to_lowercase(c);

    return lower_c == 'a' 
        || lower_c == 'e'
        || lower_c == 'i' 
        || lower_c == 'o' 
        || lower_c == 'u';
}

You may want to use some of these in your solutions.

You will be completing one of these functions!

// Functions to implement:

// 1.
// returns the number of lowercase letters in `char *string`
int count_lowercase(char *string);

// 2.
// modifies `char *string` by converting all its vowels to uppercase
void make_vowels_uppercase(char *string);

// 3..
// shortens a string so that it ends after the first word
// e.g. "This is a sentence" should turn into:
//      "This"
// 
// (hint. what defines when a string ends?)
void delete_following_words(char *string);