Concatenation in VHDL

[Altera_Forum]

Hi, 

 I have a question and maybe you can help me. I am writing a code in VHDL and I came across the following problem:  I have a four-bit input, ranging from 0 to 9 with time, called "Hundreds" and need to concatenate it with the following string: "100011". I wonder if the following code snippet work:   "100011"&hundreds;   If you do not work, how do I solve this problem?   Thank you

[Altera_Forum]

Without seeing the full code, we will have no idea. Why not try some code and compiling it?

[Altera_Forum]

Sorry... Below is the code: 

   LIBRARY ieee; USE ieee.std_logic_1164.all;  ENTITY dados_lcd IS  PORT(  clk : IN STD_LOGIC; --system clock  hundreds : IN STD_LOGIC_VECTOR(3 DOWNTO 0);  tens : IN STD_LOGIC_VECTOR(3 DOWNTO 0);  unit : IN STD_LOGIC_VECTOR(3 DOWNTO 0);  rw, rs, e : OUT STD_LOGIC; --read/write, setup/data, and enable for lcd  lcd_data : OUT STD_LOGIC_VECTOR(7 DOWNTO 0)); --data signals for lcd END dados_lcd;  ARCHITECTURE behavioral OF dados_lcd IS  SIGNAL lcd_enable : STD_LOGIC;  SIGNAL lcd_bus : STD_LOGIC_VECTOR(9 DOWNTO 0);  SIGNAL lcd_busy : STD_LOGIC;  COMPONENT lcd_controller IS  PORT(  clk : IN STD_LOGIC; --system clock  reset_n : IN STD_LOGIC; --active low reinitializes lcd  lcd_enable : IN STD_LOGIC; --latches data into lcd controller  lcd_bus : IN STD_LOGIC_VECTOR(9 DOWNTO 0); --data and control signals  busy : OUT STD_LOGIC; --lcd controller busy/idle feedback  rw, rs, e : OUT STD_LOGIC; --read/write, setup/data, and enable for lcd  lcd_data : OUT STD_LOGIC_VECTOR(7 DOWNTO 0)); --data signals for lcd  END COMPONENT; BEGIN   --instanciando o lcd_controller  dados: lcd_controller  PORT MAP(clk => clk,   reset_n => '1',   lcd_enable => lcd_enable,   lcd_bus => lcd_bus,   busy => lcd_busy,   rw => rw,   rs => rs,   e => e,   lcd_data => lcd_data );    PROCESS(clk, hundreds, tens, unit)  VARIABLE char : INTEGER RANGE 0 TO 25 := 0;  BEGIN  IF(clk'EVENT AND clk = '1') THEN  IF(lcd_busy = '0' AND lcd_enable = '0') THEN  lcd_enable <= '1';  IF(char < 25) THEN  char := char + 1;  END IF;  CASE char IS  WHEN 1 => lcd_bus <= "1001000100"; --D  WHEN 2 => lcd_bus <= "1001001001"; --I  WHEN 3 => lcd_bus <= "1001010011"; --S  WHEN 4 => lcd_bus <= "1001010100"; --T  WHEN 5 => lcd_bus <= "1010110110"; --  WHEN 6 => lcd_bus <= "1001001110"; --N  WHEN 7 => lcd_bus <= "1001000011"; --C  WHEN 8 => lcd_bus <= "1001001001"; --I  WHEN 9 => lcd_bus <= "1001000001"; --A  WHEN 10 => lcd_bus <= "1000111010"; --:  WHEN 11 => lcd_bus <= "0011000000"; --Command (cursor primeira posição da segunda linha)  WHEN 12 => lcd_bus <= "1000100000"; --SPC  WHEN 13 => lcd_bus <= "1000100000"; --SPC  WHEN 14 => lcd_bus <= "1000100000"; --SPC  WHEN 15 => lcd_bus <= "1000100000"; --SPC  WHEN 16 => lcd_bus <= "1000100000"; --SPC  WHEN 17 => lcd_bus <= "1000100000"; --SPC  WHEN 18 => lcd_bus <= "1000100000"; --SPC  WHEN 19 => lcd_bus <= "1000100000"; --SPC  WHEN 20 => lcd_bus <= "1000100000"; --SPC  WHEN 21 => lcd_bus <= "1000100000"; --SPC  WHEN 22 => lcd_bus <= "100011"&hundreds; --centenas  WHEN 23 => lcd_bus <= "100011"&tens; --dezenas  WHEN 24 => lcd_bus <= "100011"&unit; --unidades  WHEN OTHERS => lcd_enable <= '0';  END CASE;  ELSE  lcd_enable <= '0';  END IF;  END IF;  END PROCESS; END behavioral;

[Altera_Forum]

And whats the problem?

[Altera_Forum]

My question is whether it is right to do the following: 

 "100011"&hundreds  When "Hundreds" equals "1001", the result will be: "100011"&"1001" = "1000111001" ?  Thanks

[Altera_Forum]

These kind of questions can quickly and easily be checked with a compiler and simulator (quicker than using a forum) 

 Yes, this is exactly how it works.

[Altera_Forum]

Ok, thank you and apologize for the inconvenience.

[Altera_Forum]

You can try using Modelsim Altera Starter edition which is free to simulation the functional behavior of your logic.