Convert a 32 bit binary IPv4 address to its quad-dotted notation

x86-16 machine code, IBM PC DOS, 54 47 45 bytes


00000000: be82 00b3 04b1 08ac d0d8 d0d4 e2f9 8ac4  ................
00000010: 41d4 0a50 8ac4 84c0 75f6 580c 30b4 0ecd  A..P....u.X.0...
00000020: 10e2 f74b 7406 b02e cd10 ebd9 c3         ...Kt........

Build and test BIN2IP.COM using xxd -r from above.

Unassembled listing:

BE 0082     MOV  SI, 82H        ; command line input address
B3 04       MOV  BL, 4          ; loop 4 bytes 
B1 08       MOV  CL, 8          ; loop 8 bits 
AC          LODSB               ; load next bit char into AL 
D0 D8       RCR  AL, 1          ; put LSB of char into CF 
D0 D4       RCL  AH, 1          ; put CF into LSB of byte value, then shift left
E2 F9       LOOP BIT_LOOP       ; continue bit loop 
8A C4       MOV  AL, AH         ; put byte result into AL
D4 0A       AAM                 ; byte divide by 10, AH = AL / 10, AL = AL % 10 
50          PUSH AX             ; save remainder in AL on stack 
8A C4       MOV  AL, AH         ; put quotient back into AL 
41          INC  CX             ; increment decimal digit count 
D4 C0       TEST AL, AL         ; quotient = 0? 
75 F6       JNZ  GET_DIGIT      ; if not, continue looping 
58          POP  AX             ; restore digit in AL 
0C 30       OR   AL, '0'        ; ASCII convert              
B4 0E       MOV  AH, 0EH        ; BIOS write char function   
CD 10       INT  10H            ; write to console 
E2 F7       LOOP PRINT_DIGIT    ; loop until done 
4B          DEC  BX             ; is last byte? 
74 06       JZ   END_LOOP       ; if so, don't display a '.' 
B0 2E       MOV  AL, '.'        ; otherwise display '.'
CD 10       INT  10H            ; write to console 
75 D7       JNZ  BYTE_LOOP      ; continue byte loop 
C3          RET                 ; exit to DOS 


enter image description here

A standalone PC DOS executable. Input is command line, output to console.


The "interesting part" (converting binary string to bytes) is about 15 bytes, whereas the rest of code is writing the itoa() function to convert binary bytes into a decimal string representation for display.

  • -2 bytes eliminating unnecessary PUSH/POP thx to @PeterCordes!

05AB1E, 6 bytes


Try it online or verify all test cases.


4ä       # Convert the (implicit) input-string into 4 equal-sized parts
  C      # Convert each part from binary to an integer
   '.ý  '# Join this list by "."
         # (after which the result is output implicitly)

C (gcc), 48 bytes


Takes as input a 32-bit integer.

Thanks to ceilingcat and gastropner for getting this answer where it is now!

Try it online!