Add string_set_char function

README.md

@@ -5030,7 +5030,12 @@ reallocation of the underlying array of char has to be performed.
 
 ##### char string\_get\_char(const string\_t v, size\_t index)
 
-Return the byte 'index' of the string 'v'.
+Return the byte at position 'index' of the string 'v'.
+'index' shall be within the allowed range of bytes of the string.
+
+##### void string\_set\_char(string\_t v, size\_t index, const char c)
+
+Set the byte at position 'index' of the string 'v' to 'c'.
 'index' shall be within the allowed range of bytes of the string.
 
 ##### bool string\_empty\_p(const string\_t v)

m-string.h

@@ -239,6 +239,15 @@ string_get_char(const string_t v, size_t index)
   return string_get_cstr(v)[index];
 }
 
+/* Set the selected character of the string */
+static inline void
+string_set_char(string_t v, size_t index, const char c)
+{
+  M_STR1NG_CONTRACT (v);
+  M_ASSERT_INDEX(index, string_size(v));
+  m_str1ng_get_cstr(v)[index] = c;
+}
+
 /* Test if the string is empty or not */
 static inline bool
 string_empty_p(const string_t v)

tests/test-mstring.c

@@ -133,6 +133,9 @@ static void test0(void)
   string_set_str (s1, "Hello, world!");
   assert (string_size(s1) == 13);
   assert (string_get_char(s1, 1) == 'e');
+  string_set_char(s1, 1, 'E');
+  assert (string_get_char(s1, 1) == 'E');
+  string_set_char(s1, 1, 'e');
 
   string_clean(s1);
   assert (string_size(s1) == 0);