58
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Introduction

In the error outputs of some languages such as Java, a pointer is shown to give the programmer an idea of exactly where the error went wrong.

Take this example on Ideone:

Main.java:12: error: ';' expected
    Invalid Java!
                ^

Notice the caret shows where the invalid code is?

Challenge

Your challenge is: given number N and string S, place a pointer on the Nth character in S.

Examples

Input: 2, "Lorem ipsum, dollar sit amet."

Output:

Lorem ipsum, dollar sit amet.
 ^

Rules

  • Input is received via STDIN or function parameters
  • Output is printed out to the console or returned
  • Trailing new lines, spaces etc are allowed in the output
  • The pointer character must be a ^ caret and must be on a new line.
  • This is code golf, so the shortest answer wins. Good luck!
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16
  • 16
    \$\begingroup\$ I feel like this is an extremely simple problem, so I am not certain it will be received overly well. You might want to try the sandbox once you have enough rep. \$\endgroup\$ Commented Jun 10, 2015 at 1:08
  • 9
    \$\begingroup\$ I think this could have been made a bit more interesting if the input had multiple lines, so that you had to insert a newline, spaces, and carat at the correct position(s). Honestly, the spec doesn't really say it will be a single line, but I think enforcing that now will invalidate a few answers unfairly, since there's no example that shows this. \$\endgroup\$
    – Geobits
    Commented Jun 10, 2015 at 2:04
  • 3
    \$\begingroup\$ Like I said, the cat's probably out of the bag on this one. Rule changes after valid answers are posted usually don't work out well. Live and learn ;) \$\endgroup\$
    – Geobits
    Commented Jun 10, 2015 at 3:06
  • 1
    \$\begingroup\$ @SohamChowdhury I'll just pretend that was intentional ;) Do you want me to fix it? \$\endgroup\$
    – Matt Y
    Commented Jun 10, 2015 at 9:36
  • 11
    \$\begingroup\$ While this may be very simple, you've certainly done well for a first challenge! You have +16/-0 votes, 1,300 views, and 28 answers (as of this writing) and you've made the Hot Network Questions list. Nice job! \$\endgroup\$
    – Alex A.
    Commented Jun 10, 2015 at 14:50

89 Answers 89

2
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Integral, 7 6 Bytes

▼8gv^►

Try it!

-1 thanks to @petStorm

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1
  • \$\begingroup\$ Save a byte (▼8gv^► (6 bytes)) by using the v instruction. \$\endgroup\$
    – user96495
    Commented Aug 8, 2020 at 10:18
2
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Python 3, 29 bytes 31

lambda N,S:S+'\n'+' '*~-N+'^'

Try it online!

A Plain Comprehensible snippet, used function lambda function and concatenation

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4
  • \$\begingroup\$ (N-1) can be ~-N. You can also use f-strings for 28 bytes \$\endgroup\$
    – Jo King
    Commented Aug 8, 2020 at 8:36
  • \$\begingroup\$ @JoKing Thank you for your opinion \$\endgroup\$
    – Eesa
    Commented Aug 8, 2020 at 9:49
  • 1
    \$\begingroup\$ If you are using a def function declaration, you have to include it in the byte count (right now this is neither a full program nor a function). \$\endgroup\$ Commented Aug 8, 2020 at 11:19
  • \$\begingroup\$ @JoKing Sorry, my mistake. Thank you once again. \$\endgroup\$
    – Eesa
    Commented Aug 8, 2020 at 16:43
2
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Hexagony, 37 bytes (Side Length 4)

?},$;}<..0~\>(</,<}.>/>;/@\'$'65;\94\
    ? } , $
   ; } < . .
  0 ~ \ > ( <
 / , < } . > /
  > ; / @ \ '
   $ ' 6 5 ;
    \ 9 4 \

Input is of the form: "[number] [string]" ex: 3 Hello World! would output:

Hello World!
  ^

In terms of pictures, I've split it up into: Most of the program, and the End

enter image description here

Red: ?},$

  `?}` gets the pointer num and moves the MP
  `,` skips the space
  `$` creates a jump to the for loop

Red / Orange ,<;

  `,` gets the next byte from stdin
  `<` goes out of loop if byte is <= 0
  `;` prints the byte

Green ~0;56'$

  `~0` when Hexagony reads an empty byte, it puts a -1 in memory, 
       I then flip that to 1 and append a 0 to get 10
       This saves 1 char over `*10` which I needed to save
  `;` prints the newline
  `56` appends a 56 to the 10 to get 1056
       taken modulo 256, it comes out to 32 which is ascii
       for space; this also saves 1 char over `*32`
  `'` moves the MP back to the pointer num
  `$` jumps into the space printing loop

Green / Blue (<};'

  `(` decrements by 1 before checking if 0 so that it
      prints pointer val - 1 spaces
  `<` loops if counter > 0
  `};'` moves to the memory value containing the space,
        prints it, then moves back

Purple }'94

  `}'` the `'` was already in the path, so I used } to move it forward
       so it would move back
  `94` puts ascii `^` into memory

enter image description here

Starting from where purple left off, I was lucky that the program basically worked itself out. It ends up not changing the 94 in memory until it prints it, and then eventually makes its way to a blank space that hadn't been used and so I put the stopping point there and it all worked out. Fun challenge!

Try it online!

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2
+100
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APL (Dyalog Unicode), 23 bytes

⊣,(⎕UCS 10),'^',⍨' '⍴⍨⊢

Try it online!

Explanation:

⊣,(⎕UCS 10),'^',⍨' '⍴⍨⊢
⊣,(⎕UCS 10)              ⍝ original line + linefeed
            '^',⍨' '⍴⍨⊢  ⍝ generate the pointer

Explaining the generator by example:
               ('^',⍨' '⍴⍨⊢)
               {'^',⍨' '⍴⍨⍵}
               {(' '⍴⍨⍵),'^'}
               {(⍵⍴' '),'^'}
                (⍵⍴' ')          ⍝ generate ⍵ spaces
                        '^'      ⍝ append the pointer
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4
  • \$\begingroup\$ I think you need to output the original line as well. \$\endgroup\$
    – Razetime
    Commented Dec 20, 2020 at 12:01
  • \$\begingroup\$ oh true that, let me fix it \$\endgroup\$ Commented Dec 20, 2020 at 12:03
  • \$\begingroup\$ alright, should work now \$\endgroup\$ Commented Dec 20, 2020 at 12:08
  • \$\begingroup\$ {↑⍺('^',⍨⍵⍴'')} or ↑⊣,⍥⊂'^',⍨''⍴⍨⊢ with the latter being ↑⊣⍮'^',⍨''⍴⍨⊢ in Extended. \$\endgroup\$
    – Adám
    Commented Feb 18, 2021 at 6:47
1
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SpecBAS - 34

1 INPUT n,s$: PRINT s$'TAB n-1;"^"

Apostrophe in PRINT forces a new line, then just have to move the cursor to correct position.

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1
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GolfScript 11

n@~(' '*'^'

Test here.

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1
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JavaScript - 52 bytes

Here's mine, it's pretty simple.

function f(n,s){return s+"\n"+Array(n).join(" ")+"^"}

Usage:

$ console.log(f(7, "Any string at all"))

Any string at all
      ^

It points at the seventh character.

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2
  • \$\begingroup\$ Nice save Scimonster O_O \$\endgroup\$
    – Nebula
    Commented Jun 10, 2015 at 15:10
  • 1
    \$\begingroup\$ You can write it like alert((P=prompt)()+"\n"+Array(P()+1).join(" ")+"^"). And you save 2 bytes. Also, you can make it into a stasksnippet to showcase the code running. That expects the string to come first, then the position \$\endgroup\$ Commented Jun 10, 2015 at 19:53
1
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Perl 5, 31

sub{"$_[0]
"." "x($_[1]-1)."^"}
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2
  • \$\begingroup\$ You can save 2-3 characters. Drop the final newline as it's not required, then change the first newline to a literal newline. (Perl is okay with multi-line strings) \$\endgroup\$
    – Mr. Llama
    Commented Jun 10, 2015 at 16:10
  • \$\begingroup\$ @Mr.Llama thanks, those are good. \$\endgroup\$
    – hobbs
    Commented Jun 10, 2015 at 16:12
1
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Perl, 45

This is a pretty horribly golfed answer, but it's my first attempt at code golf.

<>=~/(.*), "(.*)"/;print"$2
"." "x($1-1)."^";
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1
  • 1
    \$\begingroup\$ Welcome to PPCG! If you enjoy Perl, reading Tips for golfing in Perl? is a must. Using the -p switch (counted as 1 byte), you can eliminate <>=~ and replace print with $_=. If you take a few liberties with the input format on top of that, you can shorten your code to /\d+ /;$_=$'.$"x($&-1)."^". \$\endgroup\$
    – Dennis
    Commented Jun 11, 2015 at 5:57
1
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F#, 31 characters

let p n s=s+"\n"+"^".PadLeft(n)
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1
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Ruby, 17 23 22

->s,n{s+$/+?\s*~-n+?^}

This is as short as I can go from something like this:

# Lambdas are like Procs, except with a fixed num of arguments
lambda do |sourceLine, offset|
    # The last expression is returned as the lambda's return value.
    # Multiplying a string by N will repeat it N times.
    sourceLine + "\n" + " " * (offset - 1) + "^"
end
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5
  • 1
    \$\begingroup\$ And where are you outputting/returning the source code line to which the caret points? \$\endgroup\$
    – manatwork
    Commented Jun 10, 2015 at 18:28
  • \$\begingroup\$ The rules say: "Output is printed out to the console or returned". I am returning the output. \$\endgroup\$
    – boxmein
    Commented Jun 10, 2015 at 18:32
  • \$\begingroup\$ The accent was not on the action but on the subject: your proc neither receives nor returns the source code. \$\endgroup\$
    – manatwork
    Commented Jun 10, 2015 at 18:35
  • \$\begingroup\$ Oh, sorry! Edited the code. \$\endgroup\$
    – boxmein
    Commented Jun 10, 2015 at 18:51
  • 1
    \$\begingroup\$ You can save 1 char by replacing ?\n with $/. \$\endgroup\$
    – Tony Ellis
    Commented Jun 11, 2015 at 8:39
1
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Perl, 20

After seeing @Digital Trauma's answer, I wanted to port his answer to Perl to show an another example of accepting the input numbers as unary as a default. This is based on the meta discussion.

$i++&y/1/ /&s/ $/^/

19 characters +1 for -p flag.

Run with:

{ echo "Lorem ipsum, dollar sit amet."; echo 111; } | perl -pe'$i++?y/1/ /&&s/ $/^/:1'
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2
  • \$\begingroup\$ The ternary operator seems pointless here as you only have instruction for the “then” branch: $i++&y/1/ /&s/ $/^/. \$\endgroup\$
    – manatwork
    Commented Jun 12, 2015 at 15:17
  • \$\begingroup\$ @manatwork good call! updated answer \$\endgroup\$
    – hmatt1
    Commented Jun 12, 2015 at 15:19
1
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C, 60 49

f(n,s){puts(s);while(n-=1)putch(' ');putch('^');}

First post, so I guess it's not that good.

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0
1
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Scala (49 42 bytes)

def p(i:Int,s:String)=s+"\n"+" "*(i-1)+"^"

scala> def p(i:Int,s:String)=s+"\n"+" "*(i-1)+"^"
p: (i: Int, s: String)String

scala> p(2, "Lorem ipsum, dollar sit amet.")
res0: String =
Lorem ipsum, dollar sit amet.
 ^
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1
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J, 19

Including parentheses!

The verb:

(],:'^',~' '#~<:@[)

Use:

9 (],:'^',~' '#~<:@[) 'Invalid Java!'
Invalid Java!
        ^
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1
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This is my first code golf, but here I go.

Haskell, 36

f s n=s++'\n':replicate(n-1)' '++"^"

The regular version being

placeCaret :: String -> Integer -> String
placeCaret s n = s ++ '\n' : replicate (n - 1) ' ' ++ "^"

So, not really much change. Clearly, the replicate is wasting the most space here, but as far as I know there are no alternatives in Prelude. I played a bit with other things which could have been cool tricks, but they all ended up being the same length.

Example usage:

Prelude> putStrLn $ f ['a'..'z'] 7
abcdefghijklmnopqrstuvwxyz
      ^

putStrLn is needed so that the newline will be displayed as a newline instead of "\n" (in GHCi only).

I know I'm VERY late to this party, but whatever.

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1
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Straw, 13 bytes

<#<>
> ,}*>^>

Try it online!

^ is the only non-alphanumeric character (with \) to not be assigned to a command, so no need for a string literal to push it.

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1
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Haskell, 30 bytes

s!n=s++'\n':([1..n]>>" ")++"^"
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1
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C++ (with the standard library) - 159 121 bytes (-38 by Riley)

#include<iostream>
using namespace std;int main(int c,char**v){cout<<string(v[2])<<endl<<string(stoi(v[1])-1,' ')<<"^";}

Gets input from the command line args.
Example usage: ./a.out 8 "hello, world"

This is my first ever code golf, so if you have any tips, that would be great!

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3
  • \$\begingroup\$ 1. Unless specified, you can assume the input will be correctly formatted. That lets you skip the exit part. 2. You shouldn't need to assign p and s. I think you can just put stoi(...) and string(...) right in the cout. 3. I don't think you need the space in char** v. I hope this helps :) \$\endgroup\$
    – Riley
    Commented Feb 2, 2017 at 14:52
  • \$\begingroup\$ @Riley Thanks! That helped. \$\endgroup\$
    – Admicos
    Commented Feb 2, 2017 at 15:00
  • \$\begingroup\$ You shouldn't need the space in stoi either. \$\endgroup\$
    – Riley
    Commented Feb 2, 2017 at 15:04
1
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Vim 9 bytes

jD@"a <esc>r^

Try it online!

Note that <esc> is a single byte, namely 0x1B, but since that byte is unprintable, I added a flag and used <esc> instead. This version uses the unprintable.

Explanation:

j               " Move down one line
 D              " Delete everything on this line, and save it in the unnamed register
  @"            " 'n' times
    a <esc>     " Append a 'space'
           r^   " Replace this last space with caret
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1
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Common Lisp, 40 35

(format t"~A
~VT^"(read)(1-(read)))

-5 bytes thanks to PrzemysławP.

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2
  • \$\begingroup\$ (format t"~A<enter>~VT^"(read)(1-(read))) saves 5 bytes \$\endgroup\$
    – user65167
    Commented May 13, 2017 at 17:57
  • \$\begingroup\$ @PrzemysławP Thanks, I edited the answer; I was pretty busy, sorry for the delay \$\endgroup\$
    – coredump
    Commented Jun 7, 2017 at 8:19
1
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Underload, 23 bytes

(S(
)S()(( )S^)!!^(^)S)

Assumes S is a string on the stack. N should be given in unary. It should be a sequence of : in between the ) and ! on the second line. For example:

(S(
)S()(( )S^)::::!!^(^)S)

The :::: represents N=4.

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2
  • \$\begingroup\$ Hmm, is that really the tersest way to subtract 1 in Underload? I recognise the general shape, but it's disappointing if there isn't a shorter way. \$\endgroup\$
    – user62131
    Commented Jun 7, 2017 at 9:49
  • \$\begingroup\$ @ais523 Switching to unary input for n works, because : is easily undone using !. \$\endgroup\$ Commented Jun 11, 2017 at 23:31
1
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Perl 5 -n, 20 bytes

say<>;say$"x--$_,'^'

Try it online!

Unlike a previous answer of the same byte count, this does not require the input to be in unary.

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1
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Momema, 50 bytes

1+*-8-1s00*-9-9*0s=+1*0-9 10c01+*1-1-9 32c=*1-9 94

Try it online!

Explanation

1   +*-8-1  #  mem[1] = mem[-8] + (-1)   #  a = getnum() - 1
s   0       #  do {                      #  do {
0   *-9     #    mem[0] = mem[-9]        #    b = getchar()
-9  *0      #    mem[-9] = mem[0]        #    putchar(b)
s   =+1*0   #  } while (mem[0] + 1)      #  } while (b != -1)
-9  10      #  mem[-9] = 10              #  putchar('\n')
c   0       #  do {                      #  do {
1   +*1-1   #    mem[1] = mem[1] + (-1)  #    a = a - 1
-9  32      #    mem[-9] = 32            #    putchar(32)
c   =*1     #  } while (mem[1])          #  } while (b != 0)
-9  94      #  mem[-9] = 94              #  putchar(94)

Memory addresses -8 and -9 are memory-mapped for numeric and character IO respectively.

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1
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Keg, 9 bytes

᠀
¿; ℠*\^

Try it online!

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1
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Rust, 32 bytes

|n,s|print!("{}
{:>2$}",s,"^",n)

Try it online

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1
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Brain-Flak -A, 116 bytes

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

Try it online!

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1
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05AB1E, 7 bytes

'^I<ú‚»

Try it online!

Explantion

'^       # push caret
  I<ú    # prepend with input-1 spaces
     ‚   # pair with second input
      »  # join by newline
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1
  • 2
    \$\begingroup\$ 6 bytes by taking the inputs in reversed order. \$\endgroup\$ Commented Aug 7, 2020 at 8:38
1
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J, 9 bytes

,:'^'{.~-

Try it online!

        -   negate the number
  '^'{.~    take that many characters from the string "^"
,:          append 2 items
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1
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Zsh -F, 20 bytes

printf %s\\n%*c $@ ^

Try it online!

Method stolen from the C answer.

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