打印自身的程序

main(a){printf(a,34,a="main(a){printf(a,34,a=%c%s%c,34);}",34);}

char*f="char*f=%c%s%c;main(){printf(f,34,f,34,10);}%c";main(){printf(f,34,f,34,10);}

#define q(k)main(){return!puts(#k"\nq("#k")");}
q(#define q(k)main(){return!puts(#k"\nq("#k")");})

/* A simple quine (self-printing program), in standard C. */

/* Note: in designing this quine, we have tried to make the code clear
 * and readable, not concise and obscure as many quines are, so that
 * the general principle can be made clear at the expense of length.
 * In a nutshell: use the same data structure (called "progdata"
 * below) to output the program code (which it represents) and its own
 * textual representation. */

#include <stdio.h>

void quote(const char *s)
     /* This function takes a character string s and prints the
      * textual representation of s as it might appear formatted in C
      * code. */
{
    int i;

    printf("    \"");
    for (i = 0; s[i]; i++) {
        /* Certain characters are quoted. */
        if (s[i] == '\\')
            printf("\\\\");
        else if (s[i] == '"')
            printf("\\\"");
        else if (s[i] == '\n')
            printf("\\n");
        /* Others are just printed as such. */
        else
            printf("%c", s[i]);
        /* Also insert occasional line breaks. */
        if (i % 48 == 47)
            printf("\"\n    \"");
    }
    printf("\"");
}

/* What follows is a string representation of the program code, from
 * beginning to end (formated as per quote() function, above), except
 * that the string _itself_ is coded as two consecutive '@'
 * characters. */
const char progdata[] =
    "/* A simple quine (self-printing program), in st"
    "andard C. */\n\n/* Note: in designing this quine, "
    "we have tried to make the code clear\n * and read"
    "able, not concise and obscure as many quines are"
    ", so that\n * the general principle can be made c"
    "lear at the expense of length.\n * In a nutshell:"
    " use the same data structure (called \"progdata\"\n"
    " * below) to output the program code (which it r"
    "epresents) and its own\n * textual representation"
    ". */\n\n#include <stdio.h>\n\nvoid quote(const char "
    "*s)\n     /* This function takes a character stri"
    "ng s and prints the\n      * textual representati"
    "on of s as it might appear formatted in C\n      "
    "* code. */\n{\n    int i;\n\n    printf(\"    \\\"\");\n "
    "   for (i = 0; s[i]; i++) {\n        /* Certain c"
    "haracters are quoted. */\n        if (s[i] == '\\\\"
    "')\n            printf(\"\\\\\\\\\");\n        else if ("
    "s[i] == '\"')\n            printf(\"\\\\\\\"\");\n       "
    " else if (s[i] == '\\n')\n            printf(\"\\\\n\""
    ");\n        /* Others are just printed as such. *"
    "/\n        else\n            printf(\"%c\", s[i]);\n "
    "       /* Also insert occasional line breaks. */"
    "\n        if (i % 48 == 47)\n            printf(\"\\"
    "\"\\n    \\\"\");\n    }\n    printf(\"\\\"\");\n}\n\n/* What "
    "follows is a string representation of the progra"
    "m code, from\n * beginning to end (formated as pe"
    "r quote() function, above), except\n * that the s"
    "tring _itself_ is coded as two consecutive '@'\n "
    "* characters. */\nconst char progdata[] =\n@@;\n\nin"
    "t main(void)\n     /* The program itself... */\n{\n"
    "    int i;\n\n    /* Print the program code, chara"
    "cter by character. */\n    for (i = 0; progdata[i"
    "]; i++) {\n        if (progdata[i] == '@' && prog"
    "data[i + 1] == '@')\n            /* We encounter "
    "two '@' signs, so we must print the quoted\n     "
    "        * form of the program code. */\n        {"
    "\n            quote(progdata);    /* Quote all. *"
    "/\n            i++;                /* Skip second"
    " '@'. */\n        } else\n            printf(\"%c\","
    " progdata[i]);  /* Print character. */\n    }\n   "
    " return 0;\n}\n";

int main(void)
     /* The program itself... */
{
    int i;

    /* Print the program code, character by character. */
    for (i = 0; progdata[i]; i++) {
        if (progdata[i] == '@' && progdata[i + 1] == '@')
            /* We encounter two '@' signs, so we must print the quoted
             * form of the program code. */
        {
            quote(progdata);    /* Quote all. */
            i++;                /* Skip second '@'. */
        } else
            printf("%c", progdata[i]);  /* Print character. */
    }
    return 0;
}

((lambda (x) (list x (list (quote quote) x)))
 (quote (lambda (x) (list x (list (quote quote) x)))))

((lambda (x) (list x `',x)) '(lambda (x) (list x `',x)))

((lambda (list) (list list `',list))
 '(lambda (list) (list list `',list)))

#1=(setq *print-circle* '#1#)

(identity -)

((lambda (x) `(,(reverse x) ',x)) '(`(,(reverse x) ',x) (x) lambda))

(let ((a "(let ((a %c%s%c)) (format a 34 a 34))")) (format a 34 a 34))

b=\\;bb=$b$b$b$b;q=\';x='echo "b=$bb;bb=\$b\$b\$b\$b;q=$b$q;x=$q$x$q";echo $x'
echo "b=$bb;bb=\$b\$b\$b\$b;q=$b$q;x=$q$x$q";echo $x

#! /bin/sh
q="'" qq='echo \#! /bin/sh;echo q=\"$q\" qq=${q}$qq$q;echo eval \$qq'
eval $qq

#!/bin/cat
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