Overview of Ada.Strings.Unbounded

The Ada.Strings.Unbounded package defines an unbounded string type called Unbounded_String. This type is implemented using access types (similar to pointers in other languages) and dynamically allocated memory, which means the strings can grow or shrink as needed without the programmer having to deal with the low-level memory management tasks.

For general purpuse text, especially where strings can be manipulated as necessary, this is the type that should be used.

This works best in a runtime environment such as a desktop or when resources are plentiful and exceeding your character buffer will not result in a catastrophic crash of the application. In embedded systems, this string type should never be used.

Key Features and Functions

To_Unbounded_String

Converts regular Ada strings or string literals to Unbounded_String.

Assign

Copies the content of one Unbounded_String to another.

Append

Concatenates one Unbounded_String to another or appends a regular string or character.

Insert

Inserts a string at a specified position within an Unbounded_String.

Delete

Removes a portion of the string starting at a given index for a specified length.

Length

Returns the length of the Unbounded_String.

Is_Empty

Checks if the Unbounded_String is empty.

To_String

Converts an Unbounded_String back to a regular Ada string.

Element

Accesses a character at a specific position.

Examples

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;

procedure Test_Unbounded_Strings is
   U1, U2 : Unbounded_String;
   begin
   -- Initialize unbounded strings from literals
   U1 := To_Unbounded_String("Hello");
   U2 := To_Unbounded_String(" World!");

   -- Append U2 to U1
   Append(U1, U2);

   -- Print the concatenated result
   Put_Line("Concatenated String: " & To_String(U1));

   -- Insert a string
   Insert(Source => To_Unbounded_String("Big "), Target => U1, Position => 1);

   -- Print the modified string
   Put_Line("Modified String: " & To_String(U1));

   -- Show length of the string
   Put_Line("Length of String: " & Integer'Image(Length(U1)));

   end Test_Unbounded_Strings;

---

with Ada.Text_IO.Unbounded_IO;

with Ada.Strings.Unbounded;

procedure Unbounded_Strings is

  US : Ada.Strings.Unbounded.Unbounded_String 
     := Ada.Strings.Unbounded.To_Unbounded_String("Hello, ");
  US2 : Ada.Strings.Unbounded.Unbounded_String 
      := Ada.Strings.Unbounded.To_Unbounded_String("World!");
  US_NULL : Ada.Strings.Unbounded.Unbounded_String 
      := Ada.Strings.Unbounded.Null_Unbounded_String;
begin
  Ada.Text_IO.
  Put_Line( 
     Ada.Strings.Unbounded.
     To_String(
       US));

  Ada.Strings.Unbounded.
  Append(US, US2);

  Ada.Strings.Unbounded.
  Append(Temp1, "  From Ada!");

  -- Len
  Ada.Text_IO.Put_Line("Temp1 length: " &
    Natural'Image(Ada.Strings.Unbounded.Length(Temp1)));

end Unbounded_Strings;


Name : Unbounded_String;   -- declares a string variable

with Ada.Strings.Unbounded;
with Ada.Text_IO;

procedure Print_Name_List is
  use Ada.Strings.Unbounded;
  use Ada.Text_IO;
  type Department is (HR, Sales, Development);
  Name_List : array (Department, 1 .. 3)
    of Ada.Strings.Unbounded.Unbounded_String;
  begin
    Name_List :=
      (
        ( To_Unbounded_String("John"),
          To_Unbounded_String("Michel"),
          To_Unbounded_String("Mathew")
          ),
        ( To_Unbounded_String("Bob"),
          To_Unbounded_String("Jacob"),
          To_Unbounded_String("Heiko")
          ),
        ( To_Unbounded_String("Mery"),
          To_Unbounded_String("Jane"),
          To_Unbounded_String("Heiko")
          ));
    for dept in Name_List'Range(1) loop
      for who in Name_List'Range(2) loop
        Put(To_String(Name_List(dept, who)) & " ");
        end loop;
      New_Line;
      end loop;
  end Print_Name_List;

-- function Get_Line[(File : in File_Type)] return Unbounded_String;
-- procedure Get_Line ([File : in File_Type; ]Item : out Unbounded_String);
----------------------
with Ada.Strings.Unbounded, Ada.Text_IO.Unbounded_IO;
...
S1, S2: Ada.Strings.Unbounded.Unbounded_String;
...
S1 := Ada.Text_IO.Unbounded_IO.Get_Line;
Ada.Text_IO.Unbounded_IO.Get_Line (S2);
-----------------------
with Ada.Strings.Unbounded, Ada.Text_IO, Ada.Text_IO.Unbounded_IO;
...
S1, S2: Ada.Strings.Unbounded.Unbounded_String;
F     : Text_IO.File_Type;
...
S1 := Ada.Text_IO.Unbounded_IO.Get_Line (F);
Ada.Text_IO.Unbounded_IO.Get_Line (F, S2);

-- procedure Put([File : in File_Type;] Item : in Unbounded_String);
-----------------
with Ada.Strings.Unbounded, Ada.Text_IO.Unbounded_IO;
...
S1 : Unbounded_String;
...
Put (S1);
------------------
with Ada.Strings.Unbounded;    use Ada.Strings.Unbounded;
with Ada.Text_IO.Unbounded_IO; use Ada.Text_IO.Unbounded_IO;
with Text_IO;                  use Text_IO;
...
S1 : Unbounded_String;
F  : File_Type;
...
Put (F, S1);

Put Line

procedure Put_Line ([File : in File_Type; ]Item : in Unbounded_String);

with Ada.Strings.Unbounded, Ada.Text_IO.Unbounded_IO;
use  Ada.Strings.Unbounded, Ada.Text_IO.Unbounded_IO;
...
S1 : Unbounded_String;
...
Put_Line (S1);

with Ada.Strings.Unbounded;    use Ada.Strings.Unbounded;
with Ada.Text_IO.Unbounded_IO; use Ada.Text_IO.Unbounded_IO;
with Text_IO;                  use Text_IO;
...
S1 : Unbounded_String;
F  : File_Type;
...
Put_Line (F, S1);