diff --git a/c-programming/strings/str_replace.h b/c-programming/strings/str_replace.h
index 6a04c69..4cbc90f 100644
--- a/c-programming/strings/str_replace.h
+++ b/c-programming/strings/str_replace.h
@@ -11,8 +11,12 @@
 #include <stdlib.h>
 #include <string.h>
 
+// macros
+// : parameters
+// : : count of replacements
 #define STR_REPLACE_ALL 0
 
+// function definitions
 char* str_replace(
   const char* str,
   const char* substr,