diff --git a/Anna et Ethan/regexp.c b/Anna et Ethan/regexp.c
new file mode 100644
index 0000000..83d8bc7
--- /dev/null
+++ b/Anna et Ethan/regexp.c	
@@ -0,0 +1,133 @@
+#include "regexp.h"
+
+bool reg_issimple(regexp *expression) {
+    if (expression == NULL) return true;
+    if (expression->op == INTER || expression->op == COMPLEMENT) return false;
+    return reg_issimple(expression->left) && reg_issimple(expression->right);
+}
+
+void reg_free(regexp *expression) {
+    if (expression == NULL) return;
+    reg_free(expression->left);
+    reg_free(expression->right);
+    free(expression);
+    return;
+}
+
+regexp *reg_copy(regexp *expression) {
+    if (expression == NULL) return NULL;
+    // on alloue de la mémoire pour la copie
+    regexp *copy = malloc(sizeof(regexp));
+    // on copie les champs de l'expression
+    copy->op = expression->op;
+    copy->letter = expression->letter;
+    // on copie les sous-expressions de manière récursive
+    copy->left = reg_copy(expression->left);
+    copy->right = reg_copy(expression->right);
+    // on retourne la copie effectuée
+    return copy;
+}
+
+regexp *reg_empty(void) {
+    regexp *ptr = malloc(sizeof(regexp));
+    if (ptr == NULL) {
+        ERROR("reg_empty : malloc failed");
+    } else {
+        ptr->op = EMPTY;
+        ptr->letter = '\0';
+        ptr->left = NULL;
+        ptr->right = NULL;
+    }
+    return ptr;
+}
+
+regexp *reg_epsilon(void) {
+    regexp *ptr = malloc(sizeof(regexp));
+    if (ptr == NULL) {
+        ERROR("reg_epsilon : malloc failed");
+    } else {
+        ptr->op = EPSILON;
+        ptr->letter = '\0';
+        ptr->left = NULL;
+        ptr->right = NULL;
+    }
+    return ptr;
+}
+
+regexp *reg_letter(char c) {
+    regexp *ptr = malloc(sizeof(regexp));
+    if (ptr == NULL) {
+        ERROR("reg_lettre : malloc failed");
+    } else {
+        ptr->op = CHAR;
+        ptr->letter = c;
+        ptr->left = NULL;
+        ptr->right = NULL;
+    }
+    return ptr;
+}
+
+regexp *reg_union(regexp *ptr_left, regexp *ptr_right) {
+    regexp *ptr = malloc(sizeof(regexp));
+    if (ptr == NULL) {
+        ERROR("reg_union : malloc failed");
+    } else {
+        ptr->op = UNION;
+        ptr->letter = '\0';
+        ptr->left = ptr_left;
+        ptr->right = ptr_right;
+    }
+    return ptr;
+}
+
+regexp *reg_inter(regexp *ptr_left, regexp *ptr_right) {
+    regexp *ptr = malloc(sizeof(regexp));
+    if (ptr == NULL) {
+        ERROR("reg_inter : malloc failed");
+    } else {
+        ptr->op = INTER;
+        ptr->letter = '\0';
+        ptr->left = ptr_left;
+        ptr->right = ptr_right;
+    }
+    return ptr;
+}
+
+regexp *reg_concat(regexp *ptr_left, regexp *ptr_right) {
+    regexp *ptr = malloc(sizeof(regexp));
+    if (ptr == NULL) {
+        ERROR("reg_concat : malloc failed");
+    } else {
+        ptr->op = CONCAT;
+        ptr->letter = '\0';
+        ptr->left = ptr_left;
+        ptr->right = ptr_right;
+    }
+    return ptr;
+}
+
+regexp *reg_star(regexp *expression) {
+    regexp *ptr = malloc(sizeof(regexp));
+    if (ptr == NULL) {
+        ERROR("reg_star : malloc failed");
+    } else {
+        ptr->op = STAR;
+        ptr->letter = '\0';
+        ptr->left = expression;
+        ptr->right = NULL;
+    }
+    return ptr;
+}
+
+regexp *reg_complement(regexp *expression) {
+    regexp *ptr = malloc(sizeof(regexp));
+    if (ptr == NULL) {
+        ERROR("reg_complement : malloc failed");
+    } else {
+        ptr->op = COMPLEMENT;
+        ptr->letter = '\0';
+        ptr->left = expression;
+        ptr->right = NULL;
+    }
+    return ptr;
+}