diff --git a/slides/cours_11.md b/slides/cours_11.md
index 1f627fa8997080cca7e3a6eb78aa944a7d20b910..40403b56675b8b06925302889b7db510354b7411 100644
--- a/slides/cours_11.md
+++ b/slides/cours_11.md
@@ -255,7 +255,8 @@ Caractère lu        Pile opérandes
 . . .
 
 ```C
-double evaluate(char* postfix) { // init stack
+double evaluate(char* postfix) { 
+    // declare and initialize stack s
     for (size_t i = 0; i < strlen(postfix); ++i) {
         if (is_operand(postfix[i])) {
             stack_push(&s, postfix[i]);