str_replace.c: label code blocks

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,