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authorTobias Klauser <tklauser@distanz.ch>2008-01-27 11:37:44 +0100
committerTobias Klauser <tklauser@xenon.tklauser.home>2008-01-27 11:37:44 +0100
commit7e0f021a9aec35fd8e6725e87e3313b101d26f5e (patch)
treeb1cacc4b24393f517aeb4610e9e1021f954307a8 /reference/C/CONTRIB/OR_PRACTICAL_C/16_3.c
Initial import (2.0.2-6)2.0.2-6
Diffstat (limited to 'reference/C/CONTRIB/OR_PRACTICAL_C/16_3.c')
-rw-r--r--reference/C/CONTRIB/OR_PRACTICAL_C/16_3.c159
1 files changed, 159 insertions, 0 deletions
diff --git a/reference/C/CONTRIB/OR_PRACTICAL_C/16_3.c b/reference/C/CONTRIB/OR_PRACTICAL_C/16_3.c
new file mode 100644
index 0000000..958e544
--- /dev/null
+++ b/reference/C/CONTRIB/OR_PRACTICAL_C/16_3.c
@@ -0,0 +1,159 @@
+/********************************************************
+ * words -- scan a file and print out a list of words *
+ * in ASCII order. *
+ * *
+ * Usage: *
+ * words <file> *
+ ********************************************************/
+#include <stdio.h>
+#include <ctype.h>
+#include <string.h>
+#include <stdlib.h> /* ANSI Standard only */
+
+struct node {
+ struct node *right; /* tree to the right */
+ struct node *left; /* tree to the left */
+ char *word; /* word for this tree */
+};
+
+/* the top of the tree */
+static struct node *root = NULL;
+
+main(int argc, char *argv[])
+{
+ void scan(char *); /* scan the files for words */
+ void print_tree(struct node *);/* print the words in the file */
+
+ if (argc != 2) {
+ (void) fprintf(stderr, "Error:Wrong number of parameters\n");
+ (void) fprintf(stderr, " on the command line\n");
+ (void) fprintf(stderr, "Usage is:\n");
+ (void) fprintf(stderr, " words 'file'\n");
+ exit(8);
+ }
+ scan(argv[1]);
+ print_tree(root);
+ return (0);
+}
+/********************************************************
+ * scan -- scan the file for words *
+ * *
+ * Parameters *
+ * name -- name of the file to scan *
+ ********************************************************/
+void scan(char *name)
+{
+ char word[100]; /* word we are working on */
+ int index; /* index into the word */
+ int ch; /* current character */
+ FILE *in_file; /* input file */
+
+ /* enter a word into the tree */
+ void enter(struct node **, char *);
+
+ in_file = fopen(name, "r");
+ if (in_file == NULL) {
+ (void) fprintf(stderr,
+ "Error:Unable to open %s\n", name);
+ exit(8);
+ }
+ while (1) {
+ /* scan past the whitespace */
+ while (1) {
+ ch = fgetc(in_file);
+
+ if (isalpha(ch) || (ch == EOF))
+ break;
+ }
+
+ if (ch == EOF)
+ break;
+
+ word[0] = ch;
+ for (index = 1; index < sizeof(word); index++) {
+ ch = fgetc(in_file);
+ if (!isalpha(ch))
+ break;
+ word[index] = ch;
+ }
+ /* put a null on the end */
+ word[index] = '\0';
+
+ enter(&root, word);
+ }
+ (void) fclose(in_file);
+}
+/********************************************************
+ * enter -- enter a word into the tree *
+ * *
+ * Parameters *
+ * node -- current node we are looking at *
+ * word -- word to enter *
+ ********************************************************/
+void enter(struct node **node, char *word)
+{
+ int result; /* result of strcmp */
+
+ char *save_string(char *); /* save a string on the heap */
+ void memory_error(void); /* tell user no more room */
+
+ /* see if we have reached the end */
+ if ((*node) == NULL) {
+ (*node) = (struct node *) malloc(sizeof(struct node));
+ if ((*node) == NULL)
+ memory_error();
+ (*node)->left = NULL;
+ (*node)->right = NULL;
+ (*node)->word = save_string(word);
+ }
+ result = strcmp((*node)->word, word);
+ if (result == 0)
+ return;
+ if (result < 0)
+ enter(&(*node)->right, word);
+ else
+ enter(&(*node)->left, word);
+}
+/********************************************************
+ * save_string -- save a string on the heap *
+ * *
+ * Parameters *
+ * string -- string to save *
+ * *
+ * Returns *
+ * pointer to malloc-ed section of memory with *
+ * the string copied into it. *
+ ********************************************************/
+char *save_string(char *string)
+{
+ char *new_string; /* where we are going to put string */
+
+ new_string = malloc((unsigned) (strlen(string) + 1));
+ if (new_string == NULL)
+ memory_error();
+ (void) strcpy(new_string, string);
+ return (new_string);
+}
+/********************************************************
+ * memory_error -- write error and die *
+ ********************************************************/
+void memory_error(void)
+{
+ (void) fprintf(stderr, "Error:Out of memory\n");
+ exit(8);
+}
+/********************************************************
+ * print_tree -- print out the words in a tree *
+ * *
+ * Parameters *
+ * top -- the root of the tree to print *
+ ********************************************************/
+void print_tree(struct node *top)
+{
+ if (top == NULL)
+ return; /* short tree */
+
+ print_tree(top->left);
+ (void) printf("%s\n", top->word);
+ print_tree(top->right);
+}