# In how many bits do I fit

For any positive 32-bit integer (1 ≤ n ≤ 0xFFFFFFFF) output the number of bits needed to represent that integer.

# Test cases

| n    | n in binary | bits needed |
|----------------------------------|
| 1    | 1           | 1           |
| 2    | 10          | 2           |
| 3    | 11          | 2           |
| 4    | 100         | 3           |
| 7    | 111         | 3           |
| 8    | 1000        | 4           |
| 15   | 1111        | 4           |
| 16   | 10000       | 5           |
| 128  | 10000000    | 8           |
| 341  | 101010101   | 9           |

4294967295 => 11111111111111111111111111111111 => 32


So f(16) would print or return 5

This is . Shortest code in bytes wins

• This is the ceiling of the base-2 logarithm. – orlp Dec 27 '16 at 16:51
• @orlp It actually is floor(log2(num))+1 – user41805 Dec 27 '16 at 16:52
• @KritixiLithos Right. – orlp Dec 27 '16 at 18:46
• Nevermind, just realized that the distinct is important when num is a power of two. – Brian J Dec 27 '16 at 20:22
• This is a trivial challenge with a lot of trivial solutions. There are however some non-trivial solutions too. To voters: Please read the first sentence of this meta post before upvoting builtin functions. (humbly taken from this comment) – user41805 Dec 28 '16 at 8:23

# 68020 assembler, 2 4 bytes (I think)

BFFFO D0, D1
INC D1


The BFFFO instruction finds the position of the first set bit in parameter 1, and stores the result in parameter 2. I think it is a 2-byte instruction. Unfortunately, it is indexed from 0, not 1. Hence you need an INC on D1 afterwards.

# Pushy, 11 bytes

0{${h}2/;}#  Try it online! This works by continually doing x = x // 2 until x = 0, and counting the number of divisions taken: 0 \ Push a 0 (initial counter) {$     ;    \ While input > 0:
{h}       \  Increment counter
2/     \  Floordiv input by 2
}#  \ Output final counter


# PowerShell v3+, 37 34 bytes

param($n)(1..32|?{!($n-shr$_)})[0]  Try it online! • Taking input as param($n) is 3 bytes shorter -- param($n)(1..32|?{!($n-shr$_)})[0] – AdmBorkBork Jan 3 '17 at 17:12 • @TimmyD so it is! Can't believe I missed that. – briantist Jan 3 '17 at 17:14 # Groovy, 32 bytes {Long.toBinaryString(it).size()}  This is an unnamed closure. Try it here ! # MATL, 2 bytes Bn  The shortest solution in MATL seems to be just direct, by measuring the length of the binary representation (as a vector). Other options are ZlkQ, which takes the base-2 logarithm, floors it and adds 1, or YBn which converts the input to a binary string and finds the length. # J, 4 bytes #&#:  Explanation: # NB. Counts length of bit list & NB. Connects # and #: #: NB. Creates list of bits  ## K/Kona, 4 bytes #2\:  \: gets the representation of right-hand in base left-hand - in this case, base 2 of the input. # then just counts this k)2\:341 1 0 1 0 1 0 1 0 1 k)#2\:341 9  # Python 2, 22 bytes lambda n:len(bin(n))-2  Try it online! # Whitespace, 70 bytes [S S S N _Push_0][S N S _Duplicate_0][S N S _Duplicate_0][T N T T _Read_STDIN_as_integer][T T T _Retrieve][N S S N _Create_Label_LOOP][S N S _Duplicate][N T S S N _If_0_jump_to_Label_PRINT][S S S T S N _Push_2][T S T S _Integer_division][S N T _Swap_top_two][S S S T N _Push_1][T S S S _Add][S N T _Swap_top_two][N S N N _Jump_to_Label_LOOP][N S S S N _Create_Label_PRINT][S N N _Discard_top][T N S T _Print_integer]  Letters S (space), T (tab), and N (new-line) added as highlighting only. [..._some_action] added as explanation only. Try it online (with raw spaces, tabs and new-lines only). Explanation in pseudo-code: Integer i = STDIN as integer Integer r = 0 Start LOOP: if i is 0: Call function PRINT_AND_EXIT i = i integer-divided by 2 r = r + 1 Go to next iteration of LOOP function PRINT_AND_EXIT: Print r as integer Exit with error  Example run (n=16): Command Explanation Stack HEAP STDIN STDOUT STDERR SSSN Push 0 [0] SNS Duplicate top (0) [0,0] SNS Duplicate top (0) [0,0,0] TNTT Read STDIN as integer [0,0] {0:16} 16 TTT Retrieve [0,16] {0:16} NSSN Create Label_LOOP [0,16] {0:16} SNS Duplicate top (16) [0,16,16] {0:16} NTSSN If 0: Jump to Label_PRINT [0,16] {0:16} SSSTSN Push 2 [0,16,2] {0:16} TSTS Integer-divide (16/2) [0,8] {0:16} SNT Swap top two [8,0] {0:16} SSSTN Push 1 [8,0,1] {0:16} TSSS Add (0+1) [8,1] {0:16} SNT Swap top two [1,8] {0:16} NSNN Jump to Label_LOOP [1,8] {0:16} SNS Duplicate top (8) [1,8,8] {0:16} NTSSN If 0: Jump to Label_PRINT [1,8] {0:16} SSSTSN Push 2 [1,8,2] {0:16} TSTS Integer-divide (8/2) [1,4] {0:16} SNT Swap top two [4,1] {0:16} SSSTN Push 1 [4,1,1] {0:16} TSSS Add (1+1) [4,2] {0:16} SNT Swap top two [2,4] {0:16} NSNN Jump to Label_LOOP [2,4] {0:16} SNS Duplicate top (4) [2,4,4] {0:16} NTSSN If 0: Jump to Label_PRINT [2,4] {0:16} SSSTSN Push 2 [2,4,2] {0:16} TSTS Integer-divide (4/2) [2,2] {0:16} SNT Swap top two [2,2] {0:16} SSSTN Push 1 [2,2,1] {0:16} TSSS Add (2+1) [2,3] {0:16} SNT Swap top two [3,2] {0:16} NSNN Jump to Label_LOOP [3,2] {0:16} SNS Duplicate top (2) [3,2,2] {0:16} NTSSN If 0: Jump to Label_PRINT [3,2] {0:16} SSSTSN Push 2 [3,2,2] {0:16} TSTS Integer-divide (2/2) [3,1] {0:16} SNT Swap top two [1,3] {0:16} SSSTN Push 1 [1,3,1] {0:16} TSSS Add (3+1) [1,4] {0:16} SNT Swap top two [4,1] {0:16} NSNN Jump to Label_LOOP [4,1] {0:16} SNS Duplicate top (1) [4,1,1] {0:16} NTSSN If 0: Jump to Label_PRINT [4,1] {0:16} SSSTSN Push 2 [4,1,2] {0:16} TSTS Integer-divide (1/2) [4,0] {0:16} SNT Swap top two [0,4] {0:16} SSSTN Push 1 [0,4,1] {0:16} TSSS Add (4+1) [0,5] {0:16} SNT Swap top two [5,0] {0:16} NSNN Jump to Label_LOOP [5,0] {0:16} SNS Duplicate top (0) [5,0,0] {0:16} NTSSN If 0: Jump to Label_PRINT [5,0] {0:16} NSSSN Create Label_PRINT [5,0] {0:16} SNN Discard top [5] {0:16} TNST Print as integer [] {0:16} 5 error  Program stops with an error: No exit found. # Befunge-98 (PyFunge), 19 16 bytes, Thanks to @JoKing &#\<_$.@j3:/2\+1


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19 bytes:

&0#;1+\2/:!3j@.\$_\;


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5 bytes shorter than Befunge-93 :)

# Brain-Flak, 48 bytes

({<({<(({}[()]))>{()(<{}({}[()])>)}{}}{})>()}{})


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({< # Start a loop

#devide by two:
({<(({}[()]))>{()(<{}({}[()])>)}{}}{})

>()} # Count interations
{} # pop the zero
) # push the result