listints and part of mywc done

.gitignore

@@ -4,5 +4,7 @@
 
 *.out
 .vscode/
+.gdb_history
 
-concordance/
+concordance/
+etc/

Week 9/1_listints/s1_listints.c

@@ -0,0 +1,150 @@
+
+// SOLUTION 1 - DYNAMIC MEMORY WITH realloc()
+
+/*
+* 1. Write a C program, named listints, which will print the integers requested
+  via a single command-line argument. The list of integers is to appear in 
+  strictly increasing order, with each requested integer appearing once and only
+  once (even if duplicated in the request).
+* Simple examples of its use are:
+    prompt> listints 8
+    will print:  8
+
+    prompt> listints 3,5,9
+    will print:  3 5 9
+
+    prompt> listints 1-10
+    will print:  1 2 3 4 5 6 7 8 9 10
+
+    prompt> listints 1-10,6
+    will print:  1 2 3 4 5 6 7 8 9 10
+* 🌶 🌶 And some much more difficult examples:
+    prompt> listints 2000-2020,40-50
+    prompt> listints 1-10,2010-2020,3000000-3000010
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define RANGE_SEP '-'
+#define LIST_SEP ','
+
+typedef struct {
+    long start;
+    long end;
+} RANGE;
+
+int sort_range(const void *v1, const void *v2)
+{
+    RANGE* range_1 = (RANGE*)v1;
+    RANGE* range_2 = (RANGE*)v2;
+    return (range_1->start - range_2->start);
+}
+
+char *substr(char *str, char *end)
+{
+    size_t length = end - str;
+    char *substring = malloc(length + 1);
+    strncpy(substring,str,length);
+    *(substring+length) = '\0';
+    return substring;
+}
+
+RANGE convert_to_range(char *range_str)
+{
+    char *sep = strchr(range_str, RANGE_SEP);
+    RANGE range;
+    if (sep != NULL) {
+        sep++;
+        range.start = atol(substr(range_str,sep-1));
+        range.end   = atol(sep);
+    } else {
+        range.start = atol(range_str);
+        range.end = range.start;
+    }
+
+    if (range.end < range.start) {
+        fprintf(stderr, "ERROR: End range must be before start range.\n");
+        exit(EXIT_FAILURE);
+    }
+    return range;
+}
+
+RANGE *split_ranges(char *list, size_t *list_size)
+{
+    size_t range_list_max = 1;
+    RANGE *range_list = malloc(sizeof(RANGE));
+    if (range_list == NULL) {
+        fprintf(stderr, "ERROR: Couldn't allocate memory.\n");
+        exit(EXIT_FAILURE);
+    }
+    RANGE *range = range_list;
+
+    char *end;
+    while ( (end = strchr(list, LIST_SEP)) != NULL ) {
+        // EXTRACT ONE RANGE.
+        char *element = substr(list, end);
+
+        // EXPAND MEMORY
+        if (*list_size >= range_list_max) {
+            range_list_max *= 2;
+            range_list = realloc(range_list, range_list_max * sizeof(RANGE));
+            if (range_list == NULL) {
+                fprintf(stderr, "ERROR: Couldn't allocate memory.\n");
+                exit(EXIT_FAILURE);
+            }
+            range = range_list + *list_size;
+        }
+
+        *range = convert_to_range(element);
+        range++;
+        
+        *list_size = (size_t)(range - range_list);
+        list = end + 1;
+    }
+
+    qsort(range_list, *list_size, sizeof(RANGE), sort_range);    
+    return range_list;
+}
+
+long max(long v1, long v2)
+{
+    if (v1 < v2) {
+        return v2;
+    }
+    return v1;
+}
+
+void print_ranges(RANGE *range_list, size_t list_size)
+{
+    long max_number = 0;
+    for (size_t i = 0; i < list_size; i++) {
+        RANGE *range = range_list + i;
+        for (size_t n = max(range->start, max_number); n <= range->end; n++)
+        {
+            max_number = n+1;
+            printf("%lu ",n);
+        }
+    }
+    putchar('\n');
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2)
+    {
+        fprintf(stderr, "Usage: listints [INTEGER RANGE]\n");
+        exit(EXIT_FAILURE);
+    }
+    
+    // STRING WITH A ',' APPENDED TO MAKE THE SPLIT WORK.
+    char *ext_str = malloc(strlen(argv[1]) + 1);
+    strcpy(ext_str,argv[1]);
+    strcat(ext_str,",");
+
+    size_t list_size = 0;
+    RANGE *range_list = split_ranges(ext_str, &list_size);
+    print_ranges(range_list, list_size);
+    return 0;
+}

Week 9/1_listints/s2_listints.c

@@ -0,0 +1,145 @@
+
+// SOLUTION 1 - NO DYNAMIC MEMORY ALLOCATION
+
+/*
+* 1. Write a C program, named listints, which will print the integers requested
+  via a single command-line argument. The list of integers is to appear in 
+  strictly increasing order, with each requested integer appearing once and only
+  once (even if duplicated in the request).
+* Simple examples of its use are:
+    prompt> listints 8
+    will print:  8
+
+    prompt> listints 3,5,9
+    will print:  3 5 9
+
+    prompt> listints 1-10
+    will print:  1 2 3 4 5 6 7 8 9 10
+
+    prompt> listints 1-10,6
+    will print:  1 2 3 4 5 6 7 8 9 10
+* 🌶 🌶 And some much more difficult examples:
+    prompt> listints 2000-2020,40-50
+    prompt> listints 1-10,2010-2020,3000000-3000010
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define RANGE_SEP '-'
+#define LIST_SEP ','
+
+typedef struct {
+    long start;
+    long end;
+} RANGE;
+
+int sort_range(const void *v1, const void *v2)
+{
+    RANGE* range_1 = (RANGE*)v1;
+    RANGE* range_2 = (RANGE*)v2;
+    return (range_1->start - range_2->start);
+}
+
+char *substr(char *str, char *end)
+{
+    size_t length = end - str;
+    char *substring = malloc(length + 1);
+    strncpy(substring,str,length);
+    *(substring+length) = '\0';
+    return substring;
+}
+
+RANGE convert_to_range(char *range_str)
+{
+    char *sep = strchr(range_str, RANGE_SEP);
+    RANGE range;
+    if (sep != NULL) {
+        sep++;
+        range.start = atol(substr(range_str,sep-1));
+        range.end   = atol(sep);
+    } else {
+        range.start = atol(range_str);
+        range.end = range.start;
+    }
+
+    if (range.end < range.start) {
+        fprintf(stderr, "ERROR: End range must be before start range.\n");
+        exit(EXIT_FAILURE);
+    }
+    return range;
+}
+
+RANGE *split_ranges(char *list, size_t list_size)
+{
+    RANGE *range_list = malloc(list_size * sizeof(RANGE));
+    if (range_list == NULL) {
+        fprintf(stderr, "ERROR: Couldn't allocate memory.\n");
+        exit(EXIT_FAILURE);
+    }
+    RANGE *range = range_list;
+
+    char *end;
+    while ( (end = strchr(list, LIST_SEP)) != NULL ) {
+        // EXTRACT ONE RANGE.
+        char *element = substr(list, end);
+        *range = convert_to_range(element);
+        range++;
+        list = end + 1;
+    }
+
+    qsort(range_list, list_size, sizeof(RANGE), sort_range);    
+    return range_list;
+}
+
+long max(long v1, long v2)
+{
+    if (v1 < v2) {
+        return v2;
+    }
+    return v1;
+}
+
+void print_ranges(RANGE *range_list, size_t list_size)
+{
+    long max_number = 0;
+    for (size_t i = 0; i < list_size; i++) {
+        RANGE *range = range_list + i;
+        for (size_t n = max(range->start, max_number); n <= range->end; n++)
+        {
+            max_number = n+1;
+            printf("%lu ",n);
+        }
+    }
+    putchar('\n');
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2)
+    {
+        fprintf(stderr, "Usage: listints [INTEGER RANGE]\n");
+        exit(EXIT_FAILURE);
+    }
+    
+    // STRING WITH A ',' APPENDED TO MAKE THE SPLIT WORK.
+    char *ext_str = malloc(strlen(argv[1]) + 1);
+    strcpy(ext_str,argv[1]);
+    strcat(ext_str,",");
+
+    // COUNT RANGES REQUIRED.
+    size_t ranges = 0;
+    size_t i = 0;
+    char c;
+    while ((c = ext_str[i]) != '\0') {
+        i++;
+        if (c == ',') {
+            ranges++;
+        }
+    }    
+
+    RANGE *range_list = split_ranges(ext_str, ranges);
+    print_ranges(range_list, ranges);
+    return 0;
+}

Week 9/3_mywc/mywc.c

@@ -0,0 +1,110 @@
+/*
+* 3. Both Linux and macOS provide a standard command named wc (an abbreviation for
+  wordcount!) which determines the number of lines, words, and characters in a
+  named file. You can read about this command using the online documentation: 
+  (man wc).
+* For this task, you will develop your own version of the wc program named mywc.
+
+* a. Firstly, write a function named counter() that calculates and prints out
+  the number of lines contained within a file. Your counter() function should
+  take one argument, a character array that provides a filename.
+* b. Next, modify your mywc program and the counter() function to either count
+  the lines of a file, named on the command-line, or to count the input
+  "arriving" via the stdin stream. We often described such a program as a
+  filter.
+* c. Next, extend your counter() function so that it now also counts, and 
+  prints, the number of characters and words found in the file. Be careful with 
+  the meaning of a "word" - it's just a sequence of any characters surrounded by
+  whitespace characters. Check your printed results against those of the 
+  standard wc program.
+* d. Next, observe that our counter() function is printing its three 
+  results - as we can only return a single result. Modify the counter() function
+  so that its three calculated results are now "given" back to the calling
+  function through pointers passed as parameters. Now, the calling function will
+  have the results placed in its own local variables, and be able to print
+  (or use) the results itself.
+
+* 4. 🌶 Now, using the standard getopt() function introduced in Lecture 17, add
+  support for command-line options to your mywc utility from Task-3.
+* Add command-line options to request:
+
+    -c to report the number of characters,
+    -l to report the number of lines,
+    -L to report the maximum line length (as supported on Linux, but not macOS),
+       and
+    -w to report the number of words.
+
+* Ensure that your program still works with meaningful defaults if no options
+  are provided on the command-line.
+* Ensure that your program checks that the provided command-line arguments are
+  sensible - if they are not, issue an appropriate error message to stderr after
+  all options have been processed.
+*/
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <ctype.h>
+
+void counter_stats(FILE *file, int *lines, int *words, int *characters)
+{
+    char buffer[BUFSIZ];
+    // PROCESS IN CHUNKS
+    bool word = false;
+    while ( fgets(buffer, BUFSIZ, file) != NULL ) {
+        char *c = &buffer[0];
+        while ( *c != '\0' ) {
+            // COUNT WORDS
+            if (word && isspace(*c)) {
+                (*words)++;
+                word = false;
+            } else if (!word) {
+                word = true;
+            }
+            // COUNT CHARACTERS
+            (*characters)++;
+            // COUNT NEWLINES
+            if ( *c == '\n' ) {
+                (*lines)++;
+            }
+            c++;
+        }
+    }
+}
+
+// NUMBER OF LINES IN A FILE.
+void counter(char *path, int *lines, int *words, int *characters)
+{
+    FILE *file;
+    if (path == NULL) {
+        file = stdin;
+    } else {
+        file = fopen(path, "r");
+    }
+    
+    if (file != NULL) {
+        counter_stats(file, lines, words, characters);
+    } else {
+        fprintf(stderr, "Error reading file.\n");
+        exit(EXIT_FAILURE);
+    }
+    
+}
+
+int main(int argc, char *argv[])
+{
+    char *file = argv[1];
+    // CHECK IF WE ARE ACCEPTING INPUT FROM A PIPE.
+    if (argc > 2) {
+        fprintf(stderr, "Usage: mywc [FILE]\n");
+        exit(EXIT_FAILURE);
+    }
+    
+    int lines;
+    int words;
+    int characters;
+    counter(argv[1], &lines, &words, &characters);
+    printf( "LINES %d, WORDS %d, CHARACTERS %d\n",
+            lines, words, characters  );
+    return 0;
+}

Week 9/3_mywc/unix-1969-1971.txt

@@ -0,0 +1,30 @@
+Unix was born in 1969 out of the mind of a computer scientist at Bell
+Laboratories, Ken Thompson. Thompson had been a researcher on the Multics
+project, an experience which spoiled him for the primitive batch computing
+that was the rule almost everywhere else. But the concept of timesharing
+was still a novel one in the late 1960s; the first speculations on it had
+been uttered barely ten years earlier by computer scientist John McCarthy
+(also the inventor of the Lisp language), the first actual deployment had
+been in 1962, seven years earlier, and timesharing operating systems were
+still experimental and temperamental beasts.
+
+Computer hardware was at that time more primitive than even people who
+were there to see it can now easily recall. The most powerful machines
+of the day had less computing power and internal memory than a typical
+cellphone of today. Video display terminals were in their infancy
+and would not be widely deployed for another six years. The standard
+interactive device on the earliest timesharing systems was the ASR-33
+teletype - a slow, noisy device that printed upper-case-only on big
+rolls of yellow paper. The ASR-33 was the natural parent of the Unix
+tradition of terse commands and sparse responses.
+
+When Bell Labs withdrew from the Multics research consortium, Ken
+Thompson was left with some Multics-inspired ideas about how to build a
+file system. He was also left without a machine on which to play a game
+he had written called Space Travel, a science-fiction simulation that
+involved navigating a rocket through the solar system. Unix began its
+life on a scavenged PDP-7 minicomputer, as a platform for the Space Travel
+game and a testbed for Thompson's ideas about operating system design.
+
+[adapted from https://www.catb.org/esr/writings/taoup/html/ch02s01.html]
+