クワイン (プログラミング)

/* 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 (formatted as per the 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\n      * in "     "C code. */\n{\n    int i;\n\n    printf(\"    \\\"\");\n "     "   for (i=0; s[i]; ++i) {\n        /* Certain cha"     "racters are quoted. */\n        if (s[i] == '\\\\')"     "\n            printf(\"\\\\\\\\\");\n        else if (s["     "i] == '\"')\n            printf(\"\\\\\\\"\");\n        e"     "lse 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 fo"     "llows is a string representation of the program "     "code,\n * from beginning to end (formatted as per"     " the quote() function\n * above), except that the"     " string _itself_ is coded as two\n * consecutive "     "'@' characters. */\nconst char progdata[] =\n@@;\n\n"     "int main(void)\n     /* The program itself... */\n"     "{\n    int i;\n\n    /* Print the program code, cha"     "racter by character. */\n    for (i=0; progdata[i"     "]; ++i) {\n        if (progdata[i] == '@' && prog"     "data[i+1] == '@')\n            /* We encounter tw"     "o '@' 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\", p"     "rogdata[i]);  /* Print character. */\n    }\n    r"     "eturn 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; } 

#include <stdio.h> int main(int argc, char** argv) { #define B(x) x; printf("  B(" #x ")\n"); #define A(x) printf("  A(" #x ")\n"); x;   B(printf("#include <stdio.h>\nint main(int argc, char** argv)\n{\n#define B(x)      x; printf(\"  B(\" #x \")\\n\");\n#define A(x) printf(\"  A(\" #x \")\\n\"); x;\n"))   A(printf("}\n")) } 

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