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Comments on Reverse an ASCII string

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Reverse an ASCII string

+11
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Your goal is to reverse an ascii string. Given a (optionally newline or null terminated) input, output your input in reverse order, optionally followed by a newline. Terminate afterward. Function answers will not be given a newline, and are not expected to output one unless they print the answer to console.

Examples

Assume all inputs are followed by a newline, and are all standard ASCII encoded.

abcdef -> fedcba
Hello, World! -> !dlroW ,olleH
racecar -> racecar

Example program

function solution(x) {
    return x.split("").reverse().join("");
}

Further clarifications

  • No, you don't have to handle nulls correctly.
  • Nor empty inputs.
code-golf
posted over 3 years ago
CC0
3y ago
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moony‭
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1 comment thread

General comments (7 comments)
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+4
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C (gcc), 62 bytes

main(){char b[99],*p=strchr(gets(b),0);for(;p-->b;)putch(*p);}

This relies on the usual gcc extension abuse. It assumes that max user input is 98 characters + null term, since this wasn't specified.

EDIT: Revisited, function-based equivalent of the above (plus I have no idea what compiler I used to get putch working, not gcc/Linux at least):

C (gcc), 53 bytes

*o;f(char*s){for(s=strchr(o=s,0);s-->o;)putchar(*s);}

Try it online!

posted over 3 years ago
2y ago
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Lundin‭
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2 comment threads

Doesn't work on my system (4 comments)
General comments (1 comment)
Doesn't work on my system
H_H‭ wrote 9 months ago
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I tested it under Linux AMD64 with GCC 10.2.1. putch isn't know and the return value of gets() get converted to a int and back to a pointer, causing it to lose the upper halve of the pointer value causing a segment fault in strchr().

Lundin‭ wrote 9 months ago
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I think it might depend on which standard lib that is used (libc/glibc and so on). The revised 53 byte version should be pure standard C however.

H_H‭ wrote 9 months ago · edited 9 months ago
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Maybe you can specify on which system you tested it? It is at least not standard C, since there is no putch() in standard C. And it probably needs a system where sizeof(int)==sizeof(char*), so that you don't lose anything after gets() return.

Lundin‭ wrote 9 months ago
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Well as it says in the (several years old) answer, I had no idea which system I got it running on when I did the edit. Might have been gcc/mingw/Windows. Anyway, probably best to refer to the function-only version.