diff --git a/courses/cunix/ex01/Makefile b/courses/cunix/ex01/Makefile
index 58d01e16..98c08213 100644
--- a/courses/cunix/ex01/Makefile
+++ b/courses/cunix/ex01/Makefile
@@ -5,7 +5,7 @@ RM				:= rm -rf
 
 LDFLAGS		    	+= -Llib
 
-CFLAGS		    	+= -Iinclude -Wall -Wextra -Werror -g
+CFLAGS		    	+= -std=c99 -Iinclude -Wall -Wextra -Werror -g
 
 SRCS				:= $(wildcard src/*.c)
 
diff --git a/courses/cunix/ex01/src/my_strlen.c b/courses/cunix/ex01/src/my_strlen.c
new file mode 100644
index 00000000..0968e280
--- /dev/null
+++ b/courses/cunix/ex01/src/my_strlen.c
@@ -0,0 +1,12 @@
+
+unsigned int my_strlen(char *str) 
+{
+    unsigned int strlen = 0;
+
+    while (str[strlen] != '\0')
+    {
+        strlen++;
+    }
+    
+    return strlen;
+}
diff --git a/courses/cunix/ex02/Makefile b/courses/cunix/ex02/Makefile
index 36920cba..428593dd 100644
--- a/courses/cunix/ex02/Makefile
+++ b/courses/cunix/ex02/Makefile
@@ -5,7 +5,7 @@ RM					:= rm -rf
 
 LDFLAGS	    		+= -Llib
 
-CFLAGS   			+= -Iinclude -Wall -Wextra -Werror -g
+CFLAGS   			+= -std=c99 -Iinclude -Wall -Wextra -Werror -g
 
 SRCS				:= $(wildcard src/*.c)
 
diff --git a/courses/cunix/ex02/src/my_strcmp.c b/courses/cunix/ex02/src/my_strcmp.c
new file mode 100644
index 00000000..19385899
--- /dev/null
+++ b/courses/cunix/ex02/src/my_strcmp.c
@@ -0,0 +1,18 @@
+int my_strcmp(char *str1, char *str2)
+{
+    int i = 0;
+
+    while ((str1[i] != '\0') || (str2[i] != '\0'))
+    {
+        if (str1[i] > str2[i]) 
+        {
+            return 1;
+        }
+        if (str1[i] < str2[i])
+        {
+            return -1;
+        }
+        i++;
+    }
+    return 0;
+}
diff --git a/courses/cunix/ex03/Makefile b/courses/cunix/ex03/Makefile
index 8183d82f..8aa542fa 100644
--- a/courses/cunix/ex03/Makefile
+++ b/courses/cunix/ex03/Makefile
@@ -5,7 +5,7 @@ RM					:= rm -rf
 
 LDFLAGS	    		+= -Llib
 
-CFLAGS		    	+= -Iinclude -Wall -Wextra -Werror -g
+CFLAGS		    	+= -std=c99 -Iinclude -Wall -Wextra -Werror -g
 
 SRCS				:= $(wildcard src/*.c)
 
diff --git a/courses/cunix/ex03/src/my_strcpy.c b/courses/cunix/ex03/src/my_strcpy.c
new file mode 100644
index 00000000..e28726b1
--- /dev/null
+++ b/courses/cunix/ex03/src/my_strcpy.c
@@ -0,0 +1,9 @@
+
+char *my_strcpy(char *dest, const char *src) 
+{
+    char *res = dest;
+
+    while ((*dest++ = *src++));
+
+    return res;
+}
diff --git a/courses/cunix/ex04/Makefile b/courses/cunix/ex04/Makefile
index 2fa7578b..c6741857 100644
--- a/courses/cunix/ex04/Makefile
+++ b/courses/cunix/ex04/Makefile
@@ -5,7 +5,7 @@ RM					:= rm -rf
 
 LDFLAGS			    += -Llib
 
-CFLAGS		    	+= -Iinclude -Wall -Wextra -Werror -g
+CFLAGS		    	+= -std=c99 -Iinclude -Wall -Wextra -Werror -g
 
 SRCS				:= $(wildcard src/*.c)
 
diff --git a/courses/cunix/ex04/src/my_atoi.c b/courses/cunix/ex04/src/my_atoi.c
new file mode 100644
index 00000000..4e4a9f74
--- /dev/null
+++ b/courses/cunix/ex04/src/my_atoi.c
@@ -0,0 +1,20 @@
+#define EXP 10
+
+int my_atoi(const char *nptr)
+{
+    int num = 0;
+    int sign = 1;
+
+    if (*nptr == '-')
+    {
+        sign = -1;
+        nptr++;
+    }
+
+    while (*nptr >= '0' && *nptr <= '9' && *nptr != '\0')
+    {
+        num = *nptr++ - '0' + num * EXP;
+    }
+
+    return num * sign;
+}
diff --git a/courses/cunix/ex04/src/my_itoa.c b/courses/cunix/ex04/src/my_itoa.c
new file mode 100644
index 00000000..78b062db
--- /dev/null
+++ b/courses/cunix/ex04/src/my_itoa.c
@@ -0,0 +1,45 @@
+#include <stdlib.h>
+#define EXP 10
+
+void my_reverse(char *src, int len)
+{
+    for (int i = 0; i < len / 2; i++)
+    {
+        char temp;
+        temp = src[i];
+        src[i] = src[len - i - 1];
+        src[len - i - 1] = temp;
+    }
+}
+
+
+char *my_itoa(int nmb)
+{
+    char *result = (char *)malloc(32);
+    char *number = result;
+    int len = 0;
+    int sign;
+
+    if ((sign = nmb) < 0)
+    {
+        nmb = -nmb;
+    }
+
+    do
+    {
+        *result++ = nmb % EXP + '0';
+        len++;
+    }
+    while ((nmb /= EXP) > 0);
+
+    if (sign < 0) 
+    {
+        len++;
+        *result++ = '-';
+    }
+
+    *result = '\0';
+    my_reverse(number, len);
+
+    return number;
+}
diff --git a/courses/cunix/ex05/Makefile b/courses/cunix/ex05/Makefile
index 43daeaa7..55b50366 100644
--- a/courses/cunix/ex05/Makefile
+++ b/courses/cunix/ex05/Makefile
@@ -7,7 +7,7 @@ RM					:= rm -rf
 
 LDFLAGS				+= -Llib
 
-CFLAGS				+= -Iinclude -Wall -Wextra -Werror -g
+CFLAGS				+= -std=c99 -Iinclude -Wall -Wextra -Werror -g
 
 SRCS				:= $(wildcard src/*.c)
 
diff --git a/courses/cunix/ex05/src/my_puts.c b/courses/cunix/ex05/src/my_puts.c
new file mode 100644
index 00000000..15742fca
--- /dev/null
+++ b/courses/cunix/ex05/src/my_puts.c
@@ -0,0 +1,13 @@
+#include<unistd.h>
+
+int my_puts(const char *s)
+{
+    while (*s != '\0')
+    {
+        write(1, s++, 1);
+    }
+
+    write(1, "\n", 1);
+
+    return 0;
+}
diff --git a/courses/cunix/ex07/Makefile b/courses/cunix/ex07/Makefile
index da37929f..dabbe54e 100644
--- a/courses/cunix/ex07/Makefile
+++ b/courses/cunix/ex07/Makefile
@@ -5,7 +5,7 @@ RM					:= rm -rf
 
 LDFLAGS				+= -Llib
 
-CFLAGS				+= -Iinclude -Wall -Wextra -Werror -g
+CFLAGS				+= -std=c99 -Iinclude -Wall -Wextra -Werror -g
 
 SRCS				:= $(wildcard src/*.c)
 
diff --git a/courses/cunix/ex07/src/linked_list.c b/courses/cunix/ex07/src/linked_list.c
new file mode 100644
index 00000000..65aa3191
--- /dev/null
+++ b/courses/cunix/ex07/src/linked_list.c
@@ -0,0 +1,123 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct node 
+{
+    void *data;
+    struct node *next;
+} node_t;
+
+
+node_t *list_create(void *data) 
+{
+    node_t *new_node = (node_t *)malloc(sizeof(node_t));
+    new_node->data = data;
+    new_node->next = NULL;
+
+    return new_node;
+}
+
+void list_destroy(node_t **head, void (*fp)(void *data)) 
+{
+    if (*head != NULL) 
+    {
+        list_destroy(&(*head)->next, fp);
+        (*fp)((*head)->data);
+        free(*head);
+        *head = NULL;
+    }
+}
+
+
+void list_push(node_t *head, void *data) 
+{
+    if (head == NULL) 
+    {
+        head = list_create(data);
+    } 
+    else 
+    {
+        node_t *new_node = list_create(data);
+
+        while (head->next != NULL) 
+        {
+            head = head->next;
+        }
+
+        head->next = new_node;
+    }
+}
+
+void list_unshift(node_t **head, void *data) 
+{
+    if (*head != NULL) 
+    {
+        node_t *new_node = (node_t *)malloc(sizeof(node_t));
+        new_node->data = data;
+        new_node->next = *head;
+        (*head) = new_node;
+    }
+}
+
+
+void *list_pop(node_t **head) 
+{
+    node_t *current = *head;
+
+    while (current->next->next != NULL)
+    {
+        current = current->next;
+    }
+
+    void *data = current->next->data;
+    free(current->next);
+    current->next = NULL;
+
+    return data;
+}
+
+void *list_shift(node_t **head) 
+{
+    node_t *first = *head;
+    *head = (*head)->next;
+    void *data = first->data;
+    free(first);
+
+    return data;
+}
+
+void *list_remove(node_t **head, int pos) 
+{
+    int i = 1;
+    node_t *current_head = *head;
+
+    while (i++ < pos && current_head->next->next)
+    {
+        current_head = current_head->next;
+    }
+
+    node_t *current = current_head->next;
+    void *data = current->data;
+    current_head->next = current->next;
+    free(current);
+
+    return data;
+}
+
+void list_print(node_t *head) 
+{
+    while (head != NULL) 
+    {
+        printf("%s", (char *)head->data);
+        head = head->next;
+    }
+}
+
+void list_visitor(node_t *head, void (*fp)(void *data)) 
+{
+    while (head != NULL) 
+    {
+        (*fp)(head->data);
+        head = head->next;
+    }
+}
diff --git a/courses/cunix/ex07/src/test.c b/courses/cunix/ex07/src/test.c
index bdb433fc..b2c6c704 100644
--- a/courses/cunix/ex07/src/test.c
+++ b/courses/cunix/ex07/src/test.c
@@ -7,7 +7,7 @@
 
 void printInt(void *data)
 {
-  printf("%s\n", data);
+  printf("%p\n", data);
 }
 
 void test_destroy_push(void *data)
diff --git a/courses/cunix/ex08/Makefile b/courses/cunix/ex08/Makefile
index 9ba2a96a..2fce43a6 100644
--- a/courses/cunix/ex08/Makefile
+++ b/courses/cunix/ex08/Makefile
@@ -5,7 +5,7 @@ RM					:= rm -rf
 
 LDFLAGS				+= -Llib
 
-CFLAGS				+= -Iinclude -Wall -Wextra -Werror -g
+CFLAGS				+= -std=c99 -Iinclude -Wall -Wextra -Werror -g
 
 SRCS				:= $(wildcard src/*.c)
 
diff --git a/courses/cunix/ex08/src/binary_tree.c b/courses/cunix/ex08/src/binary_tree.c
new file mode 100644
index 00000000..5a6e3b2a
--- /dev/null
+++ b/courses/cunix/ex08/src/binary_tree.c
@@ -0,0 +1,90 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+typedef struct node
+{
+    char *key;
+    void *data;
+    struct node *left;
+    struct node *right;
+}
+node_t;
+
+node_t *allocnode(void)
+{
+    node_t *root = malloc(sizeof(node_t));
+    return root;
+}
+
+node_t *insert(node_t *root, char *key, void *data)
+{
+    if (root == NULL)
+    {
+        root = allocnode();
+        root->key = key;
+        root->data = data;
+        root->left = NULL;
+        root->right = NULL;
+        return root;
+    }
+
+    int cmp_coff = strcmp(key, root->key);
+    if (cmp_coff < 0)
+    {
+        if (root->left == NULL)
+        {
+            root->left = insert(NULL, key, data);
+        }
+        else
+        {
+            insert(root->left, key, data);
+        }
+    }
+    else if (cmp_coff > 0)
+    {
+        if (root->right == NULL)
+        {
+            root->right = insert(NULL, key, data);
+        }
+        else
+        {
+            insert(root->right, key, data);
+        }
+    }
+    else
+    {
+        root->data = data;
+    }
+
+    return root;
+}
+
+void print_node(node_t *node)
+{
+    if (node != NULL)
+    {
+        printf("key: '%s', data: '%s'\n", node->key, (char *) node->data);
+    }
+}
+
+void visit_tree(node_t *node, void (*fp)(node_t *root))
+{
+    if (node != NULL)
+    {
+        visit_tree(node->left, fp);
+        (*fp)(node);
+        visit_tree(node->right, fp);
+    }
+}
+
+void destroy_tree(node_t *node, void (*fdestroy)(node_t *root))
+{
+    if (node != NULL)
+    {
+        destroy_tree(node->left, fdestroy);
+        destroy_tree(node->right, fdestroy);
+        (*fdestroy)(node);
+        free(node);
+    }
+}