commit b727aef8b56e63d5d785ef1bc3303da782af14f6
Author: manuelthieme <info@manuel-thieme.de>
Date:   Fri Jan 31 14:49:37 2020 +0100

    added everything i had in this folder

diff --git a/battleships.c b/battleships.c
new file mode 100644
index 0000000..7f8b38e
--- /dev/null
+++ b/battleships.c
@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+enum {
+    N_SHIPS,
+    WIDTH = 8,
+    HEIGHT = 8,
+};
+
+struct position {
+    int x;
+    int y;
+};
+
+struct ship {
+    int length;
+    struct position position;
+    char sunken;
+    char alignment;
+    char *hits;
+};
+
+struct game_state {
+    char running;
+    char board[WIDTH][HEIGHT];
+    struct ship ships[N_SHIPS];
+};
+
+struct ship create_ship(int length, struct position position);
+void delete_ship(struct ship ship);
+
+void hit(struct game_state *game_state, struct position position);
+
+struct game_state init_game_state();
+void deinit_game_state(struct game_state *game_state);
+char check_win_condition(struct game_state *game_state);
+
+struct position read_position();
+
+int main(void) {
+    struct game_state game_state = init_game_state();
+    while (game_state.running) {
+        struct position hit_position = read_position();
+        hit(&game_state, hit_position);
+        if (check_win_condition(&game_state)) {
+            game_state.running = 0;
+            printf("You win!");
+        }
+    }
+    deinit_game_state(&game_state);
+    return 0;
+}
+
+struct ship create_ship(int length, struct position position) {
+    struct ship ship = {.length = length, .position = position, .sunken = 0};
+    ship.hits = calloc(length, sizeof *ship.hits);
+    return ship;
+}
+void delete_ship(struct ship ship) {
+    free(ship.hits);
+}
+
+void hit(struct game_state *game_state, struct position position);
+
+struct game_state init_game_state() {
+    struct game_state game_state;
+    for (int i = 0; i < N_SHIPS; ++i) {
+        /* generate ship */
+    }
+}
+
+void deinit_game_state(struct game_state *game_state) {
+    for (int i = 0; i < N_SHIPS; ++i) {
+        delete_ship(game_state->ships[i]);
+    }
+}
+
+char check_win_condition(struct game_state *game_state);
+
+struct position read_position();
diff --git a/calculator.c b/calculator.c
new file mode 100644
index 0000000..95077ff
--- /dev/null
+++ b/calculator.c
@@ -0,0 +1,156 @@
+#include <stdio.h>
+
+/**
+ * calculate the sum of two numbers
+ * @param number1 first summand
+ * @param number2 second summand
+ * @return sum of the two summands
+ */
+int add(int number1, int number2);
+
+/**
+ * calculate the product of two numbers
+ * @param number1 first factor
+ * @param number2 second factor
+ * @return product of the two factors
+ */
+float multiply(int number1, float number2);
+
+/**
+ * calculate the power of two integers
+ * @param number1 basis
+ * @param number2 exponent
+ * @returns number1 to the power of number2
+ */
+int power(int number1, int number2);
+
+/**
+ * calculate the remainder of the division of two numbers
+ * @param number1 divident
+ * @param number2 divisor
+ * @returns number1 modulo number2
+ */
+int modulo(int number1, int number2);
+
+/**
+ * calculate the factorial
+ * @param number number to calculate factorial of
+ * @return number!
+ */
+int factorial(int number);
+
+/**
+ * calculate a fibonacci number
+ * @param number what fibonacci number should be computed?
+ * @returns numberth fibonacci number
+ */
+int fib(int number);
+
+int main(void) {
+    int number1;
+    int number2;
+    char operator;
+
+    printf("give me two numbers and an operator seperated by spaces\n");
+    int n_matched = scanf("%d %c %d", &number1, &operator, &number2);
+
+    if (n_matched != 3) {
+        printf("Failure!\n");
+        return 1;
+    }
+
+    switch (operator) {
+        case '+':
+        case 'a':
+        case 'A':
+            printf("%d\n", add(number1, number2));
+            break;
+        case '-':
+        case 's':
+        case 'S':
+            printf("%d\n", add(number1, -number2));
+            break;
+        case '*':
+        case 'm':
+        case 'M':
+            printf("%d\n", multiply(number1, number2));
+            break;
+        case '/':
+        case 'd':
+        case 'D':
+            printf("%f\n", multiply(number1, 1.0 / number2));
+            break;
+        case '%':
+        case 'r':
+        case 'R':
+            printf("%d\n", modulo(number1, number2));
+            break;
+        default:
+            printf("are you stupid? thats not an operator!!!1\n");
+            break;
+    }
+
+    return 0;
+}
+
+int add(int number1, int number2) {
+    return number1 + number2;
+}
+
+float multiply(int number1, float number2) {
+    /* recursive approach */
+    if (number1 == 0) {
+        return 0;
+    }
+    return number2 + multiply(number1-1, number2);
+
+    /* looping approach */
+    float multiple = 0;
+    for (int i = 0; i < number1; ++i) {
+        multiple += number2;
+    }
+    return multiple;
+
+    /* trivial approach */
+    return number1 * number2;
+}
+
+int power(int number1, int number2) {
+    /* looping approach */
+    int power_value = 1;
+    for (int i = 0; i < number2; ++i) {
+        power_value *= number1;
+    }
+    return power_value;
+
+    /* recursive approach */
+    if (number2 == 0) {
+        return 1;
+    }
+    return multiply(number1,power(number1, number2 - 1));
+}
+
+int modulo(int number1, int number2) {
+    return number1 % number2;
+}
+
+int factorial(unsigned number) {
+    if (number == 0) {
+        return 1;
+    }
+    return number * factorial(number - 1);
+}
+
+int fib(unsigned number) {
+    if (number == 0) {
+        return 0;
+    }
+    if (number == 1) {
+        return 0;
+    }
+    if (number == 2) {
+        return 1;
+    }
+
+    return fib(number - 1) + fib(number - 2);
+}
diff --git a/circle.c b/circle.c
new file mode 100644
index 0000000..90f9b40
--- /dev/null
+++ b/circle.c
@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <math.h>
+
+struct point {
+    float x;
+    float y;
+};
+
+struct circle {
+    struct point center;
+    float radius;
+    float circumference;
+    float area;
+};
+
+struct circle read_circle();
+
+struct circle complete_circle(struct circle circle);
+
+int main(void) {
+    struct circle circle;
+    circle = read_circle();
+    circle = complete_circle(circle);
+
+    printf("Circumference: %f\n", circle.circumference);
+    printf("Area: %f\n", circle.area);
+    return 0;
+}
+
+struct circle read_circle() {
+    struct circle circle;
+    printf("gimme da circ (<x,y> r): ");
+    char buf[256] = {0};
+    fgets(buf, sizeof(buf) / sizeof(buf[0]), stdin);
+    sscanf(buf, "<%f,%f> %f", &circle.center.x, &circle.center.y, &circle.radius);
+    return circle;
+}
+
+struct circle complete_circle(struct circle circle) {
+    circle.circumference = M_PI * 2 * circle.radius;
+    circle.area = M_PI * circle.radius * circle.radius;
+    return circle;
+}
diff --git a/complex.c b/complex.c
new file mode 100644
index 0000000..8575cbf
--- /dev/null
+++ b/complex.c
@@ -0,0 +1,45 @@
+#include <stdio.h>
+
+/**
+ * A Complex number consisting of real and imaginary part
+ */
+struct complex_number {
+    int real;   /**< real part of complex number */
+    int imag;   /**< imaginary part of complex number */
+};
+
+/**
+ * read a complex number from command line
+ *
+ * @returns the compex number from command line
+ */
+struct complex_number read_complex_number();
+
+/**
+ * print a complex number to command line
+ *
+ * @param number the complex number to print
+ */
+void print_complex_number(struct complex_number number);
+
+int main(void) {
+    struct complex_number number;
+    number = read_complex_number();
+    print_complex_number(number);
+
+    return 0;
+}
+
+struct complex_number read_complex_number() {
+    struct complex_number number;
+    printf("please input a complex number in form a+bi: ");
+    char buf[256] = {0};
+    fgets(buf, sizeof(buf) / sizeof(buf[0]), stdin);
+    sscanf(buf, "%d+%di", &number.real, &number.imag);
+    return number;
+}
+
+void print_complex_number(struct complex_number number) {
+    printf("%d+%di\n", number.real, number.imag);
+}
+
diff --git a/fib.c b/fib.c
new file mode 100644
index 0000000..565899f
--- /dev/null
+++ b/fib.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+
+int main(void) {
+    int fib;
+    printf("fib? fib! fib? ");
+    scanf("%d", &fib);
+
+    int current = 0;
+    int next = 1;
+
+    if (fib < 1) {
+        printf("Wait, wat?\n");
+        return 1;
+    }
+
+    if (fib == 1) {
+        printf("fib: %d\n", current);
+        return 0;
+    }
+
+    for (int i = 2; i < fib; ++i) {
+        int new = current + next;
+        current = next;
+        next = new;
+    }
+
+    printf("fib: %d\n", next);
+
+    return 0;
+}
diff --git a/hangman.c b/hangman.c
new file mode 100644
index 0000000..b7f75f4
--- /dev/null
+++ b/hangman.c
@@ -0,0 +1,102 @@
+#include <stdio.h>
+#include <string.h>
+
+char *gallows[] = {
+    "\n"
+    "\n"
+    "\n"
+    "\n"
+    "\n"
+    "\n"
+    "\n"
+    "\n"
+    "=============\n",
+    "\n"
+    "\n"
+    "\n"
+    "\n"
+    "\n"
+    "    -----\n"
+    "   /     \\\n"
+    "  /       \\\n"
+    "=============\n",
+    "\n"
+    "      |\n"
+    "      |\n"
+    "      |\n"
+    "      |\n"
+    "    -----\n"
+    "   /     \\\n"
+    "  /       \\\n"
+    "=============\n",
+    "      -----\n"
+    "      |/\n"
+    "      |\n"
+    "      |\n"
+    "      |\n"
+    "    -----\n"
+    "   /     \\\n"
+    "  /       \\\n"
+    "=============\n",
+    "      -----\n"
+    "      |/  o\n"
+    "      |  ^W^\n"
+    "      |  / \\\n"
+    "      |\n"
+    "    -----\n"
+    "   /     \\\n"
+    "  /       \\\n"
+    "=============\n",
+};
+
+void print_state(int state, char *placeholder, char *wrong_guesses);
+int check_input(char *word, char *placeholder, char input);
+
+int main(void) {
+    int state = 0;
+    char word[] = "gameover";
+    char placeholder[] = "________";
+    char wrong_guesses[6] = {0};
+
+    while (state < 5) {
+        print_state(state, placeholder, wrong_guesses);
+        char input;
+        do {
+            input = getchar();
+        } while (input == '\n');
+
+        if (check_input(word, placeholder, input)) {
+            if (strcmp(word, placeholder) == 0) {
+                printf("You won!");
+                return 0;
+            }
+        } else {
+            wrong_guesses[state] = input;
+            state++;
+            if (state == 5) {
+                printf("You lost!");
+                return 1;
+            }
+        }
+    }
+    return 0;
+}
+
+void print_state(int state, char *placeholder, char *wrong_guesses) {
+    printf(gallows[state]);
+    printf("word:  %s\n", placeholder);
+    printf("wrong: %s\n", wrong_guesses);
+}
+
+int check_input(char *word, char *placeholder, char input) {
+    int occurences = 0;
+    while (*word != '\0') {
+        if (*word == input) {
+            *placeholder = input;
+            occurences++;
+        }
+        word++;
+        placeholder++;
+    }
+    return occurences;
+}
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..9f54ff8
--- /dev/null
+++ b/main.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+int main(void) {
+    char input_character1;
+    char input_character2;
+    char input_character3;
+    char input_character4;
+    char input_character5;
+
+    printf("Char 1");
+    scanf("%c", &input_character1);
+    printf("Char 2");
+    scanf("\n%c", &input_character2);
+    printf("Char 3");
+    scanf("\n%c", &input_character3);
+    printf("Char 4");
+    scanf("\n%c", &input_character4);
+    printf("Char 5");
+    scanf("\n%c", &input_character5);
+
+    printf("%d %d %d %d %d\n", input_character1, input_character2, input_character3, input_character4, input_character5);
+
+    return 0;
+}
+
diff --git a/print_ptr.c b/print_ptr.c
new file mode 100644
index 0000000..61abe7f
--- /dev/null
+++ b/print_ptr.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int main(void) {
+    int a = 42;
+    int *pa = &a;
+    printf("%p\n", pa);
+    return 0;
+}
diff --git a/printing_strings.c b/printing_strings.c
new file mode 100644
index 0000000..8ea7f0d
--- /dev/null
+++ b/printing_strings.c
@@ -0,0 +1,38 @@
+#include <stdio.h>
+
+/**
+ * print a given string char by char using pointer arithmetic
+ * @param str string to print
+ */
+void print_string(char *str);
+
+/**
+ * similar to print_string but using recursion
+ * @param str string to print
+ */
+void print_string_rec(char *str);
+
+int main(int argc, char **argv) {
+    for (int i = 0; i < argc; ++i) {
+        print_string(*argv);
+        argv++;
+        putchar('\n');
+    }
+    return 0;
+}
+
+void print_string(char *str) {
+    while(*str != '\0') {
+        putchar(*str);
+        str++;
+    }
+}
+
+void print_string_rec(char *str) {
+    if (*str == '\0') {
+        return;
+    }
+    putchar(*str);
+    ++str;
+    print_string_rec(str);
+}
diff --git a/sheldon.c b/sheldon.c
new file mode 100644
index 0000000..9894ba4
--- /dev/null
+++ b/sheldon.c
@@ -0,0 +1,31 @@
+#include <stdio.h>
+
+int main(void) {
+    int n_knocks;
+    printf("how many knocks?\n");
+    scanf("%d", &n_knocks);
+
+    for (int i = 0; i < n_knocks; ++i) {
+        printf("Knock, knock, knock - Penny?\n");
+    }
+
+    int n_actual_knocks;
+    printf("and how many actual knocks?\n");
+    scanf("%d", &n_actual_knocks);
+
+    for (int i = 0; i < n_knocks; ++i) {
+        for (int j = 0; j < n_actual_knocks; ++j) {
+            if (j == 0) {
+                printf("Knock");
+            } else {
+                printf(", knock");
+            }
+        }
+        if (n_actual_knocks != 0) {
+            printf(" - ");
+        }
+        printf("Penny.\n");
+    }
+
+    return 0;
+}
diff --git a/tetris.c b/tetris.c
new file mode 100644
index 0000000..aa5d426
--- /dev/null
+++ b/tetris.c
@@ -0,0 +1,171 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+enum {
+    HEIGHT = 20,
+    WIDTH = 10,
+};
+
+struct position {
+    int x;
+    int y;
+};
+
+struct rotation {
+    struct position tiles[4];
+};
+
+struct brick {
+    struct rotation *states;
+    int state;
+    struct position position;
+};
+
+/************************
+ * Templates for bricks *
+ ************************/
+
+/* T Brick */
+struct rotation t_brick_rotations[4] = {
+    { /* first rotation */
+        .tiles = {
+            {.x = 2, .y = 0},
+            {.x = 1, .y = 1},
+            {.x = 2, .y = 1},
+            {.x = 2, .y = 2}
+        }
+    },
+    { /* second rotation */
+        .tiles = {
+            {.x = 2, .y = 0},
+            {.x = 1, .y = 1},
+            {.x = 2, .y = 1},
+            {.x = 3, .y = 1}
+        }
+    },
+    { /* third rotation */
+        .tiles = {
+            {.x = 2, .y = 0},
+            {.x = 2, .y = 1},
+            {.x = 3, .y = 1},
+            {.x = 2, .y = 2}
+        }
+    },
+    { /* fourth rotation */
+        .tiles = {
+            {.x = 1, .y = 1},
+            {.x = 2, .y = 1},
+            {.x = 3, .y = 1},
+            {.x = 2, .y = 2}
+        }
+    },
+
+};
+
+struct game_state {
+    char running;
+    char game_grid[WIDTH][HEIGHT];
+    struct brick current_brick;
+};
+
+enum input {
+    I_QUIT,
+    I_LEFT,
+    I_RIGHT,
+    I_DROP,
+    I_ROTATE,
+};
+
+struct game_state construct_game_state();
+
+struct brick spawn_brick();
+
+/* gravitate brick (darf der das?) */
+
+/* (optional) drop brick */
+
+/* should brick fall? */
+
+/* rotate brick */
+
+/* check for full line */
+
+/* remove full line */
+
+/* move brick */
+
+/* get input */
+
+/* evaluate input */
+
+/* brick to grid */
+
+/* loose condition */
+
+void draw_game_state(struct game_state game_state);
+
+int brick_on_position(int x, int y, struct brick brick);
+
+int main(void) {
+    struct game_state game_state = construct_game_state();
+    while (game_state.running) {
+        draw_game_state(game_state);
+        //get input
+        //evaluate input
+        //game logic
+        game_state.current_brick.position.y++;
+        sleep(1);
+    }
+}
+
+struct game_state construct_game_state() {
+    struct game_state game_state = {
+        .running = 1,
+        .game_grid = {0},
+        .current_brick = spawn_brick()
+    };
+    return game_state;
+}
+
+struct brick spawn_brick() {
+    struct brick brick = {
+        .states = t_brick_rotations,
+        .state = 0,
+        .position = {.x = 3, .y=0}
+    };
+    return brick;
+}
+
+void draw_game_state(struct game_state game_state) {
+    system("clear");
+    for (int y = 0; y < HEIGHT; ++y) {
+        printf("|");
+        for (int x = 0; x < WIDTH; ++x) {
+            if (game_state.game_grid[x][y]
+                    || brick_on_position(x, y, game_state.current_brick)) {
+                printf("O");
+            } else {
+                printf(" ");
+            }
+        }
+        printf("|\n");
+    }
+    printf("|");
+    for (int x = 0; x < WIDTH; ++x) {
+        printf("-");
+    }
+    printf("|\n");
+}
+
+int brick_on_position(int x, int y, struct brick brick) {
+    x -= brick.position.x;
+    y -= brick.position.y;
+    struct rotation *rotation = &brick.states[brick.state];
+    for (int i = 0; i < 4; ++i) {
+        if (rotation->tiles[i].x == x && rotation->tiles[i].y == y) {
+            return 1;
+        }
+    }
+    return 0;
+}
diff --git a/unassigned.c b/unassigned.c
new file mode 100644
index 0000000..297faeb
--- /dev/null
+++ b/unassigned.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int main(void) {
+    char x = 64;
+
+    printf("%c\n", x);
+    printf("%d\n", x);
+}