diff --git a/scope.c b/scope.c
new file mode 100644
index 0000000..94d45b9
--- /dev/null
+++ b/scope.c
@@ -0,0 +1,141 @@
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+
+// Scoope definition
+
+/** A scope is a set of identifiers */
+typedef struct {
+    size_t scopeSize;
+    char** identifiers;
+} scope_t ;
+
+scope_t* actualScope;
+
+/** Add a new specifier to a scope */
+int addId(char *name) {
+    ssize_t l = 0;
+    ssize_t r = actualScope->scopeSize - 1;
+    while ( l <= r ) {
+        ssize_t c = (l+r)/2;
+        int result = strcmp(name, actualScope->identifiers[c]);
+        if (result > 0) {
+            l = c + 1;
+        } else if (result < 0) {
+            r = c - 1;
+        } else {
+            /* Symbol found */
+            fprintf(stderr, "\nConflicting types for '%s' \n", name);
+            exit(0);
+            return -1;
+        }
+    }
+
+    /* Symbol does not exist */
+    char* newSpecfier = strdup(name);
+    actualScope->identifiers = realloc(actualScope->identifiers, sizeof(*actualScope->identifiers)*(actualScope->scopeSize + 1));
+    memmove(actualScope->identifiers + l + 1, actualScope->identifiers + l, sizeof(*actualScope->identifiers)*(actualScope->scopeSize - l));
+    actualScope->scopeSize++;
+    actualScope->identifiers[l] = newSpecfier;
+    return 1;
+}
+
+/** A new scopeList is pushed on an other scope : we have a stack of scopeList */
+typedef struct {
+    size_t stackSize;
+    scope_t** scopeList;
+} stackS_t;
+
+stackS_t *scopeStack;
+int zebi;
+
+/** Functions */
+void initScope() {
+    scopeStack = malloc(sizeof(scopeStack));
+    scopeStack->stackSize = 0;
+    actualScope = malloc(sizeof(actualScope));
+    actualScope->scopeSize = 0;    
+    scopeStack->scopeList = malloc(sizeof(scopeStack->scopeList));
+    scopeStack->scopeList[0] = actualScope;
+}
+
+int pushScope() {
+
+    /* A new scope is initialized */
+    scope_t* newScope = malloc(sizeof(scope_t));
+    newScope->scopeSize = 0;
+    newScope->identifiers = malloc(sizeof(newScope->identifiers));
+
+    /* A memory area is given in the stack */
+    scopeStack->scopeList = realloc(scopeStack->scopeList, sizeof(**scopeStack->scopeList)*(scopeStack->stackSize + 1));
+
+    /* And finally, actualScope is the stack that was just pushed */
+    scopeStack->stackSize++;
+    scopeStack->scopeList[scopeStack->stackSize] = newScope;
+    actualScope = newScope;
+
+    /* Everything was done well*/
+    return 1;
+} 
+
+int popScope() {
+
+    /* Verifying that we don't pop the last scope */
+    if (scopeStack->stackSize > 0) {
+
+        /* Removing the last scope */
+        scope_t* lastScope = malloc(sizeof(actualScope));
+        lastScope = scopeStack->scopeList[scopeStack->stackSize];
+        free(lastScope->identifiers);
+        free(lastScope);
+        scopeStack->stackSize--;
+        
+        /* Setting the actual scope */
+        actualScope = malloc(sizeof(actualScope));
+        actualScope = scopeStack->scopeList[scopeStack->stackSize];
+        if (actualScope == NULL) printf("LE C C NULL\n");
+        return 1;
+    
+    } else {
+
+        /* Error */
+        fprintf(stderr, "\nCan't pop the last scope\n");
+        exit(0);
+        return -1;
+
+    }
+    
+}
+
+int isTypedefed(char *s) {
+    
+    /** Latest scopes prevail */
+    if (scopeStack->scopeList == NULL) printf("null");
+    for (int i = scopeStack->stackSize ; i != 0 ; i--) {
+        scope_t* scope = malloc(sizeof(scopeStack->scopeList[i]));
+        scope = scopeStack->scopeList[i];
+        
+        if (scope->scopeSize) {
+            ssize_t l = 0;
+            ssize_t r = scope->scopeSize - 1;
+            while ( l <= r ) {
+                ssize_t c = (l+r)/2;
+                int result = strcmp(s, scope->identifiers[c]);
+                if (result > 0) {
+                    l = c + 1;
+                } else if (result < 0) {
+                    r = c - 1;
+                } else {
+                    /* Symbol found */
+                    return 1;
+                }
+            }
+        } 
+    }
+
+    /* Symbol not found */
+    return 0;
+
+}
+
+