From ad37fa6675c799d8c1280c4845643da5adf0db8e Mon Sep 17 00:00:00 2001 From: zlg Date: Sun, 8 Mar 2015 00:11:13 -0800 Subject: Solve Exercise 6-02: Common prefix printing --- ch6/6-02_common-prefix-printer.c | 239 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 239 insertions(+) create mode 100644 ch6/6-02_common-prefix-printer.c diff --git a/ch6/6-02_common-prefix-printer.c b/ch6/6-02_common-prefix-printer.c new file mode 100644 index 0000000..fedb389 --- /dev/null +++ b/ch6/6-02_common-prefix-printer.c @@ -0,0 +1,239 @@ +#include +#include +#include +#include + +/* The C Programming Language: 2nd Edition + * + * Exercise 6-2: Write a program that reads a C program and prints in + * alphabetical order each group of variable names that are identical in the + * first 6 characters, but different somewhere thereafter. Don't count words + * within string and comments. Make 6 a parameter that can be set from the + * command line. + * + * Notes: First off, "variable names" should be "words". It doesn't make sense + * otherwise. + * + * The trick to this is we can traverse the tree with no problem, but to do + * comparisons on the words, we need to know the last one we worked with. With + * two additional static variables in treeprint(), we have all we need to + * manipulate what we're outputting. + */ + +#define BUFSIZE 1000 +#define MAXWORD 100 +#define DEF_PRE_LEN 6 + +struct key { + char *word; + int count; +}; +struct tnode { + char *word; + int count; + struct tnode *left; + struct tnode *right; +}; + +enum states { + NORMAL, + INQUOTE, + INCOMMENT +}; +char buf[BUFSIZE]; +int bufp = 0; +int state = NORMAL; +int minlen; + +int getch(void); +void ungetch(int); +int getword(char *, int); +struct key *binsearch(char *, struct key *, int); +struct tnode *addtree(struct tnode *, char *); +void treeprint(struct tnode *, int); +struct tnode *talloc(void); +char *mystrdup(char *); +int check_prefix(char *, char*, int); + +int main(int argc, char *argv[]) { + switch (argc) { + case 1: + minlen = DEF_PRE_LEN; + break; + case 2: + minlen = strtol(argv[1], NULL, 10); + break; + default: + printf("Too many arguments.\n"); + return 1; + } + struct tnode *root; + char word[MAXWORD]; + root = NULL; + while (getword(word, MAXWORD) != EOF) { + /* Only add the words we need to the tree */ + if (isalpha(word[0]) && strlen(word) > minlen) { + root = addtree(root, word); + if (root == NULL) { + printf("No words at that length or greater were found.\n"); + return 1; + } + } + } + treeprint(root, minlen); + return 0; +} + +int getword(char *word, int lim) { + int c; + char *w = word; + while (isspace(c = getch())) { + } + if (c != EOF && c != '#' && c != '"' && c != '/' && c != '*') { + *w++ = c; + } + if (c == '*' && state == INCOMMENT) { + if ((c = getch()) == '/') { + state == NORMAL; + return '/'; + } + } + /* Ignore comments */ + if (c == '/') { + c = getch(); + if (c == '/') { + while ((c = getch()) != EOF && c != '\n') { + } + return '*'; + } + if (c == '*') { + state = INCOMMENT; + return '*'; + } + } + /* Handle quotes */ + if (c == '"') { + state = INQUOTE; + } + if (state == INQUOTE) { + while ((c = getch()) != '"' && c != EOF) { + } + state = NORMAL; + } + /* Ignore preprocessor lines */ + if (c == '#') { + while ((c = getch()) != '\n' && c != EOF) { + } + } + /* Add exceptions for underscores */ + if (!isalpha(c) && c != '_') { + *w = '\0'; + return c; + } + for ( ; --lim > 0; w++) { + if (!isalnum(*w = getch()) && *w != '_') { + ungetch(*w); + break; + } + } + *w = '\0'; + return word[0]; +} + +struct key *binsearch(char *word, struct key *tab, int n) { + int cond; + struct key *low = &tab[0]; + struct key *high = &tab[n]; + struct key *mid; + while (low < high) { + mid = low + (high-low) / 2; + if ((cond = strcmp(word, mid->word)) < 0) { + high = mid; + } else if (cond > 0) { + low = mid + 1; + } else { + return mid; + } + } + return NULL; +} + +int getch(void) { + return (bufp > 0) ? buf[--bufp] : getchar(); +} + +void ungetch(int c) { + if (bufp >= BUFSIZE) { + printf("ungetch: Too many characters.\n"); + } else { + buf[bufp++] = c; + } +} + +struct tnode *addtree(struct tnode *p, char *w) { + int cond; + if (p == NULL) { + p = talloc(); + p->word = mystrdup(w); + p->count = 1; + p->left = p->right = NULL; + } else if ((cond = strcmp(w, p->word)) == 0) { + p->count++; + } else if (cond < 0) { + p->left = addtree(p->left, w); + } else { + p->right = addtree(p->right, w); + } + return p; +} + +int check_prefix(char *s1, char *s2, int len) { + int i; + if (len == 0) { + return 1; + } + for (i == 0; *s1 == *s2 && *s1 != '\0' && i < len; i++, *s1++, *s2++) { + } + if (i == len) { + return 1; + } + return 0; +} + +void treeprint(struct tnode *p, int len) { + static struct tnode *last; /* The last word we saw */ + static int output = 1; /* Controls whether we output 'last' or not */ + if (p != NULL) { + treeprint(p->left, len); + if (len == 0) { + printf("%4d %s\n", p->count, p->word); + } else { + if (last != NULL) { + if (check_prefix(last->word, p->word, len)) { + if (output) { + printf("%4d %s\n", last->count, last->word); + output = 0; + } + printf("%4d %s\n", p->count, p->word); + } else { + output = 1; + } + } + last = p; + } + treeprint(p->right, len); + } +} + +struct tnode *talloc(void) { + return (struct tnode *) malloc(sizeof(struct tnode)); +} + +char *mystrdup(char *s) { + char *p; + p = (char *) malloc(strlen(s)+1); + if (p != NULL) { + strcpy(p , s); + } + return p; +} -- cgit v1.2.3-70-g09d2 highlight'> setup.py wasn't being included, preventing distros from easily building it. Whoops. 2018-10-22vgstash: let backlog filter ignore unbeatable gameszlg1-1/+1 To migrate, run these two commands: sqlite3 /path/to/vgstash.db 'DROP VIEW backlog;' vgstash init 2018-10-18Bump to 0.3beta2 for PyPIzlg1-3/+3 2018-10-18vgstash.DB.__init__: fix error output formattingzlg1-1/+1 2018-10-18README: fix inline <code> formattingzlg1-3/+4 2018-10-18cli: show msg if game to be deleted is not in DBzlg2-2/+12 2018-10-18README: expand on usage, cover shell quotingzlg1-7/+99 2018-10-18cli: Tell the user when a game lacks noteszlg2-3/+15 2018-10-18Catch when an invalid list filter is passedzlg4-3/+24 Before, vgstash.DB.list_games() would default to 'allgames' and silently hide it when a filter wasn't found. This commit ensures that the vgstash package and CLI both indicate when an invalid filter is passed to them: * vgstash.DB.list_games() will return False on a failure to match; * vgstash_cli uses Click's Choice object to enforce the constraint 2018-10-12cli: Add zero-game import/export messageszlg2-11/+18 2018-10-10Bump to 0.3beta1 for PyPIzlg1-1/+1 2018-10-10Move tests and data to dedicated directoryzlg7-10/+26 Also tweaked the export command to report correctly. 2018-10-10cli: Add "export" commandzlg2-5/+54 The export command is like the import command; currently supporting YAML output, but ready to be expanded as needed. 2018-10-10cli: Add "import" commandzlg5-1/+76 Currently the import command will only accept YAML files, but is ready for expansion to other formats as needed. 2018-10-09Bump to 0.3alpha6 for PyPIzlg1-1/+1 2018-10-09cli: Add "notes" commandzlg2-4/+74 The "notes" command will show the user what their notes for a particular game are. The output can be piped anywhere the user wants, such as a pager or a file. If "notes" is passed with the "--edit" or "-e" flag, vgstash will open a temporary file with the game's notes already inside and edit it using the program pointed to by the EDITOR environment variable. When the editor is closed (with a successful exit status), vgstash updates the game's notes and exits. The defaults for the testing environment ("cat" for non-interactive, "vim" for interactive) may need tweaking on other operating systems. Patches for these platforms are very welcome. 2018-10-09update_game: ensure notes are also savedzlg1-2/+2 2018-10-09cli: add 'update' commandzlg3-20/+92 Two helper functions were also added to the vgstash package to ease client workflows. This commit marks the final core function necessary to manipulate a vgstash DB on the command line. 2018-10-06cli: Add "delete" commandzlg2-0/+19 Unlike the old version of vgstash, the new one does not accept row IDs as arguments for removal. Instead, it accepts two mandatory arguments: the title of the game, and the system it's on. This is in line with the database itself, using the title and system as primary keys. 2018-10-06Remove ID field from DBzlg3-38/+46 The sqlite database already uses a game's title and system as the primary keys. Row IDs are redundant. 2018-10-06cli: change "Status" heading to "Progress"zlg2-36/+40 2018-09-29Bump to 0.3alpha5 for PyPIzlg1-1/+1 2018-09-29cli: Add pretty printing to 'list' commandzlg3-17/+107 Also add the "--width" option to specify the maximum width of the table. 2018-09-08setup.py: Bump to alpha4 for PyPIzlg1-1/+1 2018-09-08cli: add '--raw' option to list commandzlg2-9/+45 Add '--raw' option to the list command, in addition to proper note expansion. Newline characters in notes are escaped to be friendly to scripting. This option may be shortened to '-r' at the user's convenience. In raw output mode, the information is formatted in plain pipe-delimited strings, one line per row: title|system|ownership|progress|notes ownership and progress are printed in their numeric form, consistent with the OWNERSHIP and PROGRESS dictionaries in the vgstash package. An empty notes field will result in a line ending with a pipe and no whitespace following it. 2018-09-08Add remaining filters to vgstash packagezlg1-2/+11 2018-09-04Update LICENSE to match setup.pyzlg1-80/+67 Whoops. 2018-09-03Branch off from master with pytest, tox, clickzlg16-778/+779 This commit is huge, but contains everything needed for a "proper" build system built on pytest + tox and a CLI built with click. For now, this branch will contain all new vgstash development activity until it reaches feature parity with master. The CLI is installed to pip's PATH. Only the 'init', 'add', and 'list' commands work, with only two filters. This is pre-alpha software, and is therefore not stable yet. 2018-03-18Flesh out filter types and ownership statuszlg3-82/+144 It's time for a refactor to a module; the functionality and interface are clashing. 2018-03-18README.mdown: break line correctlyzlg1-1/+1 2018-03-18add 'playlog' list filterzlg2-2/+9 This filter is used to get an idea of which games you're currently playing through, so you can prioritize games to play when you're bored and detect it when you've beaten a game but haven't marked it as such. 2018-03-13Update helpers a bitzlg1-2/+9 At present, user modification is needed to make these seamless. vgup() may need to be axed in favor of telling the user to make an alias. 2018-03-13Make VGSTASH_DB_LOCATION point to a filezlg2-21/+20 It used to point to a directory, which would then look for .vgstash.db. This behavior was kind of backwards and I don't remember why I did it that way. This change gives users more control over where they put their DB. Be sure to update your environment variable if you have it set! 2016-11-18Remove settings from helpers.shZe Libertine Gamer1-5/+0 Sourcing them in .bash_profile screws up login if they're set. 2016-11-15Correct phrasing in README.Ze Libertine Gamer1-4/+4 2016-11-13DerpZe Libertine Gamer1-0/+1 2016-11-03Improve error handling in shell scriptsZe Libertine Gamer4-3/+23 2016-10-24Correct run_again, add recursionZe Libertine Gamer1-0/+4 Loops and functions -- oh my, what a useful combination. :) 2016-10-21Add quotes to correct behavior for arglistZe Libertine Gamer1-1/+1 2016-10-14updater.sh: add recursion, error handlingZe Libertine Gamer1-43/+101 2016-10-14Correct pipe-handling behaviorZe Libertine Gamer1-1/+9 2016-10-12Clarify a method to move between platformsZe Libertine Gamer1-2/+5 Also correct a typo.