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はじめての80386記号プログラミング B!


takesako


こんにちは。id:TAKESAKOです。

そろそろ単純な「Hello, world!」に飽きてきた頃なので、フィボナッチ数列を数えるプログラムをC言語で書いてみたいと思います。

C言語でフィボナッチ数列を数える

それではまず最初に、Cの文字列領域にフィボナッチ数列を数えるx86の32bit実行コードを書いて、それを無理やり関数呼び出しの形式にして実行してみたいと思います。

#include <stdio.h>

char x86[] = {
    0x8B, 0x4C, 0x24, 0x04, //  mov ecx,[esp+0x4]
    0x31, 0xC0,             //  xor eax,eax
    0x99,                   //  cdq
    0x49,                   //  dec ecx
    0x7F, 0x04,             //  jg 0xe
    0xE0, 0x01,             //  loopne 0xd
    0x40,                   //  inc eax
    0xC3,                   //  ret
    0x40,                   //  inc eax
    0x50,                   //  push eax
    0x01, 0xD0,             //  add eax,edx
    0x5A,                   //  pop edx
    0xE2, 0xFA,             //  loop 0xf
    0xC3,                   //  ret
};

int fibonacci(int n)
{
    int(*x86call)(int) = (void*)x86;
    return x86call(n);
}

int main(int argc, char *argv[])
{
    int n;
    int N = (argc > 1) ? atoi(argv[1]) : 46;
    for (n = 0; n <= N; n++) {
        int f = fibonacci(n);
        printf("f[%d] = %d\n", n, f);
    }
}

このファイルをa.cで保存し、gccでコンパイルして実行すると、フィボナッチ数列が高速に出力されます。

$ gcc a.c
$ ./a.out 46
f[0] = 0
f[1] = 1
f[2] = 1
f[3] = 2
f[4] = 3
f[5] = 5
f[6] = 8
f[7] = 13
f[8] = 21
f[9] = 34
f[10] = 55
f[11] = 89
f[12] = 144
f[13] = 233
f[14] = 377
f[15] = 610
f[16] = 987
f[17] = 1597
f[18] = 2584
f[19] = 4181
f[20] = 6765
f[21] = 10946
f[22] = 17711
f[23] = 28657
f[24] = 46368
f[25] = 75025
f[26] = 121393
f[27] = 196418
f[28] = 317811
f[29] = 514229
f[30] = 832040
f[31] = 1346269
f[32] = 2178309
f[33] = 3524578
f[34] = 5702887
f[35] = 9227465
f[36] = 14930352
f[37] = 24157817
f[38] = 39088169
f[39] = 63245986
f[40] = 102334155
f[41] = 165580141
f[42] = 267914296
f[43] = 433494437
f[44] = 701408733
f[45] = 1134903170
f[46] = 1836311903

全くエラーがでないのがすごいですね。

問題点

使用している文字がバイナリを含んでいるので、どうせならUS-ASCIIの範囲内で、さらに記号だけで書いてみたいですね。

このプログラムはx86が実行できるCコンパイラ(IA-32環境)でしか動作しませんが、フィボナッチ数列を計算するときに1byte命令のcdq(0x99)を個人的に使ってみたいだけでした。すみません。

記号だけのmain関数で「Hello, world!」を書いてみる

これを踏まえて、記号だけのmain関数で「Hello, world!」を書いてみます。

char main[] =
"`%@@@@%!!!!----!-:(*}-[:,>-|;|``[[[[[[[%@@@@%!!!!-"
"====-<;;;-{{{{-|{{{`[[[[[[[%@@@@%!!!!------***[-.,"
"^{-{|}{`[[[[[[[%@@@@%!!!!------}#**-{{+,-[{{|`[[[["
"[[[%@@@@%!!!!------****-.,,^-{||}`[[[[[[[%@@@@%!!!"
"!------**!*-!.{^-~!|;`[[[[[[[%@@@@%!!!!-!----+$**-"
"!!!^-!!#)`[[[[[[[%@@@@%!!!!----!-**~$->^}&-?*`$`[["
"[[[[[%@@@@%!!!!------*$$!-!!!!-#!!!`[[[[[[[%@@@@%!"
"!!!------****-.,,;-{||%`[[[[[[[%@@@@%!!!!------***"
"*-.,`^-{|`;`[[[[[[[%@@@@%!!!!------*!**-.{+,-{{{|`"
"[[[[[[[%@@@@%!!!!------%***-{&,,-{}||`[[[[[[[%@@@@"
"%!!!!------*~**-.}&#-)?}}`^^^^^^^^%@@@@%!!!!------"
"****-^^^^-*)))`________!~!%@@@@%!!!!------****-;;;"
";-.---`________!~!%@@@@%!!!!------****-===^-?>>)`_"
"_______)~!%@@@@%!!!!------***~-^^!|-!%][`________)"
"~!%@@@@%!!!!------*~**-=|^;->](/`________)~!%@@@@%"
"!!!!------~***-|&^#-]$%%`________)~!'/``````";

※プログラム中の絶対アドレスにアクセスしてint 80hのシステムコールを直接使用しているので筆者のLinux x86環境のgccでしか動作しません。(CentOS 5.2)

デモ

Linux x86 no-alnum Hello world! - TTYShare

このプログラムを実行すると無事「Hello, world!」が出力されました。

80386コードリーディング

objdump -D a.out して、実行バイナリをディスアセンブルした結果を読んでみましょう。

08049560 <main>:
 8049560:       60                      pusha
 8049561:       25 40 40 40 40          and    $0x40404040,%eax
 8049566:       25 21 21 21 21          and    $0x21212121,%eax
 804956b:       2d 2d 2d 2d 21          sub    $0x212d2d2d,%eax
 8049570:       2d 3a 28 2a 7d          sub    $0x7d2a283a,%eax
 8049575:       2d 5b 3a 2c 3e          sub    $0x3e2c3a5b,%eax
 804957a:       2d 7c 3b 7c 60          sub    $0x607c3b7c,%eax
 804957f:       60                      pusha
 8049580:       5b                      pop    %ebx
 8049581:       5b                      pop    %ebx
 8049582:       5b                      pop    %ebx
 8049583:       5b                      pop    %ebx
 8049584:       5b                      pop    %ebx
 8049585:       5b                      pop    %ebx
 8049586:       5b                      pop    %ebx
 8049587:       25 40 40 40 40          and    $0x40404040,%eax
 804958c:       25 21 21 21 21          and    $0x21212121,%eax
 8049591:       2d 3d 3d 3d 3d          sub    $0x3d3d3d3d,%eax
 8049596:       2d 3c 3b 3b 3b          sub    $0x3b3b3b3c,%eax
 804959b:       2d 7b 7b 7b 7b          sub    $0x7b7b7b7b,%eax
 80495a0:       2d 7c 7b 7b 7b          sub    $0x7b7b7b7c,%eax
 80495a5:       60                      pusha
 80495a6:       5b                      pop    %ebx
 80495a7:       5b                      pop    %ebx
 80495a8:       5b                      pop    %ebx
 80495a9:       5b                      pop    %ebx
 80495aa:       5b                      pop    %ebx
 80495ab:       5b                      pop    %ebx
 80495ac:       5b                      pop    %ebx
 80495ad:       25 40 40 40 40          and    $0x40404040,%eax
 80495b2:       25 21 21 21 21          and    $0x21212121,%eax
 80495b7:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 80495bc:       2d 2a 2a 2a 5b          sub    $0x5b2a2a2a,%eax
 80495c1:       2d 2e 2c 5e 7b          sub    $0x7b5e2c2e,%eax
 80495c6:       2d 7b 7c 7d 7b          sub    $0x7b7d7c7b,%eax
 80495cb:       60                      pusha
 80495cc:       5b                      pop    %ebx
 80495cd:       5b                      pop    %ebx
 80495ce:       5b                      pop    %ebx
 80495cf:       5b                      pop    %ebx
 80495d0:       5b                      pop    %ebx
 80495d1:       5b                      pop    %ebx
 80495d2:       5b                      pop    %ebx
 80495d3:       25 40 40 40 40          and    $0x40404040,%eax
 80495d8:       25 21 21 21 21          and    $0x21212121,%eax
 80495dd:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 80495e2:       2d 7d 23 2a 2a          sub    $0x2a2a237d,%eax
 80495e7:       2d 7b 7b 2b 2c          sub    $0x2c2b7b7b,%eax
 80495ec:       2d 5b 7b 7b 7c          sub    $0x7c7b7b5b,%eax
 80495f1:       60                      pusha
 80495f2:       5b                      pop    %ebx
 80495f3:       5b                      pop    %ebx
 80495f4:       5b                      pop    %ebx
 80495f5:       5b                      pop    %ebx
 80495f6:       5b                      pop    %ebx
 80495f7:       5b                      pop    %ebx
 80495f8:       5b                      pop    %ebx
 80495f9:       25 40 40 40 40          and    $0x40404040,%eax
 80495fe:       25 21 21 21 21          and    $0x21212121,%eax
 8049603:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 8049608:       2d 2a 2a 2a 2a          sub    $0x2a2a2a2a,%eax
 804960d:       2d 2e 2c 2c 5e          sub    $0x5e2c2c2e,%eax
 8049612:       2d 7b 7c 7c 7d          sub    $0x7d7c7c7b,%eax
 8049617:       60                      pusha
 8049618:       5b                      pop    %ebx
 8049619:       5b                      pop    %ebx
 804961a:       5b                      pop    %ebx
 804961b:       5b                      pop    %ebx
 804961c:       5b                      pop    %ebx
 804961d:       5b                      pop    %ebx
 804961e:       5b                      pop    %ebx
 804961f:       25 40 40 40 40          and    $0x40404040,%eax
 8049624:       25 21 21 21 21          and    $0x21212121,%eax
 8049629:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 804962e:       2d 2a 2a 21 2a          sub    $0x2a212a2a,%eax
 8049633:       2d 21 2e 7b 5e          sub    $0x5e7b2e21,%eax
 8049638:       2d 7e 21 7c 3b          sub    $0x3b7c217e,%eax
 804963d:       60                      pusha
 804963e:       5b                      pop    %ebx
 804963f:       5b                      pop    %ebx
 8049640:       5b                      pop    %ebx
 8049641:       5b                      pop    %ebx
 8049642:       5b                      pop    %ebx
 8049643:       5b                      pop    %ebx
 8049644:       5b                      pop    %ebx
 8049645:       25 40 40 40 40          and    $0x40404040,%eax
 804964a:       25 21 21 21 21          and    $0x21212121,%eax
 804964f:       2d 21 2d 2d 2d          sub    $0x2d2d2d21,%eax
 8049654:       2d 2b 24 2a 2a          sub    $0x2a2a242b,%eax
 8049659:       2d 21 21 21 5e          sub    $0x5e212121,%eax
 804965e:       2d 21 21 23 29          sub    $0x29232121,%eax
 8049663:       60                      pusha
 8049664:       5b                      pop    %ebx
 8049665:       5b                      pop    %ebx
 8049666:       5b                      pop    %ebx
 8049667:       5b                      pop    %ebx
 8049668:       5b                      pop    %ebx
 8049669:       5b                      pop    %ebx
 804966a:       5b                      pop    %ebx
 804966b:       25 40 40 40 40          and    $0x40404040,%eax
 8049670:       25 21 21 21 21          and    $0x21212121,%eax
 8049675:       2d 2d 2d 2d 21          sub    $0x212d2d2d,%eax
 804967a:       2d 2a 2a 7e 24          sub    $0x247e2a2a,%eax
 804967f:       2d 3e 5e 7d 26          sub    $0x267d5e3e,%eax
 8049684:       2d 3f 2a 60 24          sub    $0x24602a3f,%eax
 8049689:       60                      pusha
 804968a:       5b                      pop    %ebx
 804968b:       5b                      pop    %ebx
 804968c:       5b                      pop    %ebx
 804968d:       5b                      pop    %ebx
 804968e:       5b                      pop    %ebx
 804968f:       5b                      pop    %ebx
 8049690:       5b                      pop    %ebx
 8049691:       25 40 40 40 40          and    $0x40404040,%eax
 8049696:       25 21 21 21 21          and    $0x21212121,%eax
 804969b:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 80496a0:       2d 2a 24 24 21          sub    $0x2124242a,%eax
 80496a5:       2d 21 21 21 21          sub    $0x21212121,%eax
 80496aa:       2d 23 21 21 21          sub    $0x21212123,%eax
 80496af:       60                      pusha
 80496b0:       5b                      pop    %ebx
 80496b1:       5b                      pop    %ebx
 80496b2:       5b                      pop    %ebx
 80496b3:       5b                      pop    %ebx
 80496b4:       5b                      pop    %ebx
 80496b5:       5b                      pop    %ebx
 80496b6:       5b                      pop    %ebx
 80496b7:       25 40 40 40 40          and    $0x40404040,%eax
 80496bc:       25 21 21 21 21          and    $0x21212121,%eax
 80496c1:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 80496c6:       2d 2a 2a 2a 2a          sub    $0x2a2a2a2a,%eax
 80496cb:       2d 2e 2c 2c 3b          sub    $0x3b2c2c2e,%eax
 80496d0:       2d 7b 7c 7c 25          sub    $0x257c7c7b,%eax
 80496d5:       60                      pusha
 80496d6:       5b                      pop    %ebx
 80496d7:       5b                      pop    %ebx
 80496d8:       5b                      pop    %ebx
 80496d9:       5b                      pop    %ebx
 80496da:       5b                      pop    %ebx
 80496db:       5b                      pop    %ebx
 80496dc:       5b                      pop    %ebx
 80496dd:       25 40 40 40 40          and    $0x40404040,%eax
 80496e2:       25 21 21 21 21          and    $0x21212121,%eax
 80496e7:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 80496ec:       2d 2a 2a 2a 2a          sub    $0x2a2a2a2a,%eax
 80496f1:       2d 2e 2c 60 5e          sub    $0x5e602c2e,%eax
 80496f6:       2d 7b 7c 60 3b          sub    $0x3b607c7b,%eax
 80496fb:       60                      pusha
 80496fc:       5b                      pop    %ebx
 80496fd:       5b                      pop    %ebx
 80496fe:       5b                      pop    %ebx
 80496ff:       5b                      pop    %ebx
 8049700:       5b                      pop    %ebx
 8049701:       5b                      pop    %ebx
 8049702:       5b                      pop    %ebx
 8049703:       25 40 40 40 40          and    $0x40404040,%eax
 8049708:       25 21 21 21 21          and    $0x21212121,%eax
 804970d:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 8049712:       2d 2a 21 2a 2a          sub    $0x2a2a212a,%eax
 8049717:       2d 2e 7b 2b 2c          sub    $0x2c2b7b2e,%eax
 804971c:       2d 7b 7b 7b 7c          sub    $0x7c7b7b7b,%eax
 8049721:       60                      pusha
 8049722:       5b                      pop    %ebx
 8049723:       5b                      pop    %ebx
 8049724:       5b                      pop    %ebx
 8049725:       5b                      pop    %ebx
 8049726:       5b                      pop    %ebx
 8049727:       5b                      pop    %ebx
 8049728:       5b                      pop    %ebx
 8049729:       25 40 40 40 40          and    $0x40404040,%eax
 804972e:       25 21 21 21 21          and    $0x21212121,%eax
 8049733:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 8049738:       2d 25 2a 2a 2a          sub    $0x2a2a2a25,%eax
 804973d:       2d 7b 26 2c 2c          sub    $0x2c2c267b,%eax
 8049742:       2d 7b 7d 7c 7c          sub    $0x7c7c7d7b,%eax
 8049747:       60                      pusha
 8049748:       5b                      pop    %ebx
 8049749:       5b                      pop    %ebx
 804974a:       5b                      pop    %ebx
 804974b:       5b                      pop    %ebx
 804974c:       5b                      pop    %ebx
 804974d:       5b                      pop    %ebx
 804974e:       5b                      pop    %ebx
 804974f:       25 40 40 40 40          and    $0x40404040,%eax
 8049754:       25 21 21 21 21          and    $0x21212121,%eax
 8049759:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 804975e:       2d 2a 7e 2a 2a          sub    $0x2a2a7e2a,%eax
 8049763:       2d 2e 7d 26 23          sub    $0x23267d2e,%eax
 8049768:       2d 29 3f 7d 7d          sub    $0x7d7d3f29,%eax
 804976d:       60                      pusha
 804976e:       5e                      pop    %esi
 804976f:       5e                      pop    %esi
 8049770:       5e                      pop    %esi
 8049771:       5e                      pop    %esi
 8049772:       5e                      pop    %esi
 8049773:       5e                      pop    %esi
 8049774:       5e                      pop    %esi
 8049775:       5e                      pop    %esi
 8049776:       25 40 40 40 40          and    $0x40404040,%eax
 804977b:       25 21 21 21 21          and    $0x21212121,%eax
 8049780:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 8049785:       2d 2a 2a 2a 2a          sub    $0x2a2a2a2a,%eax
 804978a:       2d 5e 5e 5e 5e          sub    $0x5e5e5e5e,%eax
 804978f:       2d 2a 29 29 29          sub    $0x2929292a,%eax
 8049794:       60                      pusha
 8049795:       5f                      pop    %edi
 8049796:       5f                      pop    %edi
 8049797:       5f                      pop    %edi
 8049798:       5f                      pop    %edi
 8049799:       5f                      pop    %edi
 804979a:       5f                      pop    %edi
 804979b:       5f                      pop    %edi
 804979c:       5f                      pop    %edi
 804979d:       21 7e 21                and    %edi,0x21(%esi)
 80497a0:       25 40 40 40 40          and    $0x40404040,%eax
 80497a5:       25 21 21 21 21          and    $0x21212121,%eax
 80497aa:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 80497af:       2d 2a 2a 2a 2a          sub    $0x2a2a2a2a,%eax
 80497b4:       2d 3b 3b 3b 3b          sub    $0x3b3b3b3b,%eax
 80497b9:       2d 2e 2d 2d 2d          sub    $0x2d2d2d2e,%eax
 80497be:       60                      pusha
 80497bf:       5f                      pop    %edi
 80497c0:       5f                      pop    %edi
 80497c1:       5f                      pop    %edi
 80497c2:       5f                      pop    %edi
 80497c3:       5f                      pop    %edi
 80497c4:       5f                      pop    %edi
 80497c5:       5f                      pop    %edi
 80497c6:       5f                      pop    %edi
 80497c7:       21 7e 21                and    %edi,0x21(%esi)
 80497ca:       25 40 40 40 40          and    $0x40404040,%eax
 80497cf:       25 21 21 21 21          and    $0x21212121,%eax
 80497d4:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 80497d9:       2d 2a 2a 2a 2a          sub    $0x2a2a2a2a,%eax
 80497de:       2d 3d 3d 3d 5e          sub    $0x5e3d3d3d,%eax
 80497e3:       2d 3f 3e 3e 29          sub    $0x293e3e3f,%eax
 80497e8:       60                      pusha
 80497e9:       5f                      pop    %edi
 80497ea:       5f                      pop    %edi
 80497eb:       5f                      pop    %edi
 80497ec:       5f                      pop    %edi
 80497ed:       5f                      pop    %edi
 80497ee:       5f                      pop    %edi
 80497ef:       5f                      pop    %edi
 80497f0:       5f                      pop    %edi
 80497f1:       29 7e 21                sub    %edi,0x21(%esi)
 80497f4:       25 40 40 40 40          and    $0x40404040,%eax
 80497f9:       25 21 21 21 21          and    $0x21212121,%eax
 80497fe:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 8049803:       2d 2a 2a 2a 7e          sub    $0x7e2a2a2a,%eax
 8049808:       2d 5e 5e 21 7c          sub    $0x7c215e5e,%eax
 804980d:       2d 21 25 5d 5b          sub    $0x5b5d2521,%eax
 8049812:       60                      pusha
 8049813:       5f                      pop    %edi
 8049814:       5f                      pop    %edi
 8049815:       5f                      pop    %edi
 8049816:       5f                      pop    %edi
 8049817:       5f                      pop    %edi
 8049818:       5f                      pop    %edi
 8049819:       5f                      pop    %edi
 804981a:       5f                      pop    %edi
 804981b:       29 7e 21                sub    %edi,0x21(%esi)
 804981e:       25 40 40 40 40          and    $0x40404040,%eax
 8049823:       25 21 21 21 21          and    $0x21212121,%eax
 8049828:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 804982d:       2d 2a 7e 2a 2a          sub    $0x2a2a7e2a,%eax
 8049832:       2d 3d 7c 5e 3b          sub    $0x3b5e7c3d,%eax
 8049837:       2d 3e 5d 28 2f          sub    $0x2f285d3e,%eax
 804983c:       60                      pusha
 804983d:       5f                      pop    %edi
 804983e:       5f                      pop    %edi
 804983f:       5f                      pop    %edi
 8049840:       5f                      pop    %edi
 8049841:       5f                      pop    %edi
 8049842:       5f                      pop    %edi
 8049843:       5f                      pop    %edi
 8049844:       5f                      pop    %edi
 8049845:       29 7e 21                sub    %edi,0x21(%esi)
 8049848:       25 40 40 40 40          and    $0x40404040,%eax
 804984d:       25 21 21 21 21          and    $0x21212121,%eax
 8049852:       2d 2d 2d 2d 2d          sub    $0x2d2d2d2d,%eax
 8049857:       2d 7e 2a 2a 2a          sub    $0x2a2a2a7e,%eax
 804985c:       2d 7c 26 5e 23          sub    $0x235e267c,%eax
 8049861:       2d 5d 24 25 25          sub    $0x2525245d,%eax
 8049866:       60                      pusha
 8049867:       5f                      pop    %edi
 8049868:       5f                      pop    %edi
 8049869:       5f                      pop    %edi
 804986a:       5f                      pop    %edi
 804986b:       5f                      pop    %edi
 804986c:       5f                      pop    %edi
 804986d:       5f                      pop    %edi
 804986e:       5f                      pop    %edi
 804986f:       29 7e 21                sub    %edi,0x21(%esi)
 8049872:       27                      daa
 8049873:       2f                      das
 8049874:       60                      pusha
 8049875:       60                      pusha
 8049876:       60                      pusha
 8049877:       60                      pusha
 8049878:       60                      pusha
 8049879:       60                      pusha

pushaとpopとandとsubの4命令しかでてこないので、簡単ですね。

スタック上に展開されるコード

0x804974e まで実行されると、スタック上に以下のコードが展開されます

0XXXXX00 <.text>:
 XXXXX00:       b8 04 00 00 00          mov    $0x4,%eax
 XXXXX05:       bb 01 00 00 00          mov    $0x1,%ebx
 XXXXX0a:       e8 0e 00 00 00          call   0xXXXXX1d
 XXXXX0f:       48 65 6c 6c 6f 2c 20    ; "Hello, "
 XXXXX16:       77 6f 72 6c 64 21 0a    ; "world!\n"
 XXXXX1d:       59                      pop    %ecx
 XXXXX1e:       ba 0e 00 00 00          mov    $0xe,%edx
 XXXXX23:       cd 80                   int    $0x80
 XXXXX25:       b8 01 00 00 00          mov    $0x1,%eax
 XXXXX2a:       cd 80                   int    $0x80

自己書き換え

0x804986fにあるsub %edi,0x21(%esi)命令が実行されると、次の0x8049872番地がcall esp(0xff 0xd4)を実行するコードに書き変わります。

 8049872:       90                      nop
 8049873:       ff d4                   call esp
 8049875:       90                      nop

これで無事Linuxのシステムコールで「Hello, world!」の文字が標準出力に出力され(int80h,eax=4)、プログラムの終了(int80h,eax=1)も行うことができました。

簡単ですね。

次回予告

次は文字列のmain関数に使用できる記号の種類を何文字まで減らせるのか試してみたいと思います。