diff -r efbd59642577 -r 49a284f61e8c ucx/cx/string.h
--- a/ucx/cx/string.h	Fri Apr 21 21:25:32 2023 +0200
+++ b/ucx/cx/string.h	Sun May 07 11:53:10 2023 +0200
@@ -296,28 +296,50 @@
 );
 
 /**
- * Concatenates two or more strings.
+ * Concatenates strings.
  *
  * The resulting string will be allocated by the specified allocator.
-  * So developers \em must pass the return value to cx_strfree() eventually.
-  *
-  * \note It is guaranteed that there is only one allocation.
-  * It is also guaranteed that the returned string is zero-terminated.
+ * So developers \em must pass the return value to cx_strfree_a() eventually.
+ *
+ * If \p str already contains a string, the memory will be reallocated and
+ * the other strings are appended. Otherwise, new memory is allocated.
+ *
+ * \note It is guaranteed that there is only one allocation.
+ * It is also guaranteed that the returned string is zero-terminated.
  *
  * @param alloc the allocator to use
- * @param count   the total number of strings to concatenate
- * @param ...     all strings
+ * @param str   the string the other strings shall be concatenated to
+ * @param count the number of the other following strings to concatenate
+ * @param ...   all other strings
  * @return the concatenated string
  */
 __attribute__((__warn_unused_result__, __nonnull__))
-cxmutstr cx_strcat_a(
+cxmutstr cx_strcat_ma(
         CxAllocator const *alloc,
+        cxmutstr str,
         size_t count,
         ...
 );
 
 /**
- * Concatenates two or more strings.
+ * Concatenates strings and returns a new string.
+ *
+ * The resulting string will be allocated by the specified allocator.
+ * So developers \em must pass the return value to cx_strfree_a() eventually.
+ *
+ * \note It is guaranteed that there is only one allocation.
+ * It is also guaranteed that the returned string is zero-terminated.
+ *
+ * @param alloc the allocator to use
+ * @param count the number of the other following strings to concatenate
+ * @param ...   all other strings
+ * @return the concatenated string
+ */
+#define cx_strcat_a(alloc, count, ...) \
+cx_strcat_ma(alloc, cx_mutstrn(NULL, 0), count, __VA_ARGS__)
+
+/**
+ * Concatenates strings and returns a new string.
  *
  * The resulting string will be allocated by standard \c malloc().
  * So developers \em must pass the return value to cx_strfree() eventually.
@@ -325,12 +347,32 @@
  * \note It is guaranteed that there is only one allocation.
  * It is also guaranteed that the returned string is zero-terminated.
  *
- * @param count   the total number of strings to concatenate
- * @param ...     all strings
+ * @param count   the number of the other following strings to concatenate
+ * @param ...     all other strings
  * @return the concatenated string
  */
 #define cx_strcat(count, ...) \
-cx_strcat_a(cxDefaultAllocator, count, __VA_ARGS__)
+cx_strcat_ma(cxDefaultAllocator, cx_mutstrn(NULL, 0), count, __VA_ARGS__)
+
+/**
+ * Concatenates strings.
+ *
+ * The resulting string will be allocated by standard \c malloc().
+ * So developers \em must pass the return value to cx_strfree() eventually.
+ *
+ * If \p str already contains a string, the memory will be reallocated and
+ * the other strings are appended. Otherwise, new memory is allocated.
+ *
+ * \note It is guaranteed that there is only one allocation.
+ * It is also guaranteed that the returned string is zero-terminated.
+ *
+ * @param str     the string the other strings shall be concatenated to
+ * @param count   the number of the other following strings to concatenate
+ * @param ...     all other strings
+ * @return the concatenated string
+ */
+#define cx_strcat_m(str, count, ...) \
+cx_strcat_ma(cxDefaultAllocator, str, count, __VA_ARGS__)
 
 /**
  * Returns a substring starting at the specified location.
@@ -732,6 +774,35 @@
  */
 #define cx_strdup(string) cx_strdup_a(cxDefaultAllocator, string)
 
+
+/**
+ * Creates a duplicate of the specified string.
+ *
+ * The new string will contain a copy allocated by \p allocator.
+ *
+ * \note The returned string is guaranteed to be zero-terminated.
+ *
+ * @param allocator the allocator to use
+ * @param string the string to duplicate
+ * @return a duplicate of the string
+ * @see cx_strdup_m()
+ */
+#define cx_strdup_ma(allocator, string) cx_strdup_a(allocator, cx_strcast(string))
+
+/**
+ * Creates a duplicate of the specified string.
+ *
+ * The new string will contain a copy allocated by standard
+ * \c malloc(). So developers \em must pass the return value to cx_strfree().
+ *
+ * \note The returned string is guaranteed to be zero-terminated.
+ *
+ * @param string the string to duplicate
+ * @return a duplicate of the string
+ * @see cx_strdup_ma()
+ */
+#define cx_strdup_m(string) cx_strdup_a(cxDefaultAllocator, cx_strcast(string))
+
 /**
  * Omits leading and trailing spaces.
  *