Added Descending Option and Command Line Parsing

I also added some appropriate tests. It appears to work, but tests 5 and 6 appear to fail due to a problem parsing the long --descending option.

src/main.c

@@ -4,6 +4,13 @@
 #include <name_string.h>
 #include <string_vector.h>
 
+#define ASCENDING 1
+#define DESCENDING 0
+
+// Nasty global variable needed here as there is no other way to pass state to the compare function.
+// This variable should be kept static so no other unit may see it.
+static int global_sort_order = ASCENDING;
+
 /*
  * Compare function to be used by qsort. Due to the implementation in the C
  * Standard Library, this function necessarily accepts void * and must cast to
@@ -15,10 +22,16 @@ int compare(const void *str1, const void *str2)
     const string *second = *(const string **) str2;
 
     int res = compare_on_length(first, second);
-    if(res == 0)
+    if(0 == res)
     {
         return compare_on_alphabet(first, second);
     }
+
+    // The user may have requested we sort in the other direction on length
+    if(global_sort_order == DESCENDING)
+    {
+        res = -res;
+    }
     return res;
 }
 
@@ -27,24 +40,73 @@ int compare(const void *str1, const void *str2)
  * 1. Strings are sorted by length first, not alphabet.
  * 2. Strings are sorted by alphabet only if they are the same length.
  */
-void perform_length_alphabet_sort(string_vector *vector)
+void perform_length_alphabet_sort(string_vector *vector, int ascending)
 {
+    if(!ascending)
+    {
+        global_sort_order = DESCENDING;
+    }
     qsort((void *) vector->array, vector->size, sizeof(string *), compare);
 }
 
+void print_usage()
+{
+    fprintf(stderr, "Usage: name_sort [-d|--descending] <input_file>\n");
+}
+
 int main(int argc, char **argv)
 {
     if(argc < 2)
     {
-        fprintf(stderr, "Usage: name_sort <input_file>\n");
+        print_usage();
         return 1;
     }
-    FILE *file = fopen(argv[1], "r");
 
+    int ascending = 1;
+    int double_dash_found = 0;
+    string *long_descending_option = create_from_cstr("descending");
+
+    //Parse our command line options
+    size_t option_index;
+    for(option_index = 1; option_index < argc && argv[option_index][0] == '-' && !double_dash_found; option_index++)
+    {
+        switch(argv[option_index][1]) {
+            case 'd': ascending = 0; break;
+            case '-':
+                if(argv[2] == '\0') {
+                    //Double Dash with no other characters is traditional unix symbol of no more options, so we stop.
+                    double_dash_found = 1;
+                } else {
+                    string *option = create_from_cstr(argv[2]); //Pass in the remainder of the string
+                    if(compare_on_alphabet(option, long_descending_option) == 0)
+                    {
+                        ascending = 1;
+                    }
+                    else
+                    {
+                        print_usage();
+                        return 1;
+                    }
+                }
+                break;
+            default:
+                print_usage();
+                return 1;
+        }
+    }
+
+    // At the end of our loop, option_index should be pointing to all non-option arguments. In this case it should
+    // only be one argument.
+    if(option_index != argc-1)
+    {
+        print_usage();
+        return 1;
+    }
+    char *input_file = argv[option_index];
+    FILE *file = fopen(input_file, "r");
     string_vector *vector = create_vector(0);
     read_file_into_vector(file, vector);
-
-    perform_length_alphabet_sort(vector);
+    perform_length_alphabet_sort(vector, ascending);
     vector_print(vector);
     destroy_vector(vector);
     fclose(file);

test/Sorted 3.txt

@@ -0,0 +1,50 @@
+Fitzjerrell
+Hendrickson
+Clevenger
+Bostwick
+Cachedon
+Giddings
+Guenther
+Hatfield
+Kalivoda
+Kirkland
+Phillips
+Reynolds
+Sullivan
+Williams
+Byfield
+Dulaney
+Hagberg
+Hillman
+McCrave
+Michael
+Padgett
+Routson
+Starkey
+Stegman
+Adkins
+Broome
+Hickey
+Laymon
+Rogers
+Tanton
+Taylor
+Baker
+Ellis
+Evans
+Foley
+Glock
+Graff
+Heigl
+Lundy
+McVey
+Nylon
+Peery
+Reyes
+White
+Asby
+Bain
+Dean
+Fife
+Wile
+Kha

test/Sorted 4.txt

@@ -0,0 +1,10 @@
+Zachariah
+Arnold
+Barney
+George
+johnny
+Jordan
+Aaron
+abbie
+Jimmy
+Liz

test/Test.cmd

@@ -2,6 +2,8 @@ echo off
 
 SET OUTPUT="output.txt"
 SET OUTPUT2="output2.txt"
+SET OUTPUT3="output3.txt"
+SET OUTPUT4="output4.txt"
 
 if exist %OUTPUT% del /f %OUTPUT%
 NameSort.exe "Sort Me.txt" > %OUTPUT%
@@ -12,3 +14,13 @@ if exist %OUTPUT2% del /f %OUTPUT2%
 NameSort.exe "Sort Me 2.txt" > %OUTPUT2%
 fc %OUTPUT2% "Sorted 2.txt"
 if %errorlevel% EQU 0 (echo "Success") else ( echo "Failure")
+
+if exist %OUTPUT3% del /f %OUTPUT3%
+NameSort.exe "Sort Me.txt" > %OUTPUT3%
+fc %OUTPUT3% "Sorted 3.txt"
+if %errorlevel% EQU 0 (echo "Success") else ( echo "Failure")
+
+if exist %OUTPUT4% del /f %OUTPUT4%
+NameSort.exe "Sort Me 2.txt" > %OUTPUT4%
+fc %OUTPUT4% "Sorted 4.txt"
+if %errorlevel% EQU 0 (echo "Success") else ( echo "Failure")

test/Test.sh

@@ -2,12 +2,24 @@
 
 OUTPUT="output.txt"
 OUTPUT2="output2.txt"
+OUTPUT3="output3.txt"
+OUTPUT4="output4.txt"
+OUTPUT5="output5.txt"
+OUTPUT6="output6.txt"
 
 rm -f $OUTPUT
 rm -f $OUTPUT2
+rm -f $OUTPUT3
+rm -f $OUTPUT4
+rm -f $OUTPUT5
+rm -f $OUTPUT6
 
 ./NameSort "Sort Me.txt" > $OUTPUT
 ./NameSort "Sort Me 2.txt" > $OUTPUT2
+./NameSort -d "Sort Me.txt" > $OUTPUT3
+./NameSort -d "Sort Me 2.txt" > $OUTPUT4
+./NameSort --descending "Sort Me.txt" > $OUTPUT5
+./NameSort --descending "Sort Me 2.txt" > $OUTPUT6
 
 diff "Sorted.txt" $OUTPUT
 if [ $? -eq 0 ]; then
@@ -22,3 +34,31 @@ if [ $? -eq 0 ]; then
 else
     echo "Test 2 Failure"
 fi
+
+diff "Sorted 3.txt" $OUTPUT3
+if [ $? -eq 0 ]; then
+    echo "Test 3 Success"
+else
+    echo "Test 3 Failure"
+fi
+
+diff "Sorted 4.txt" $OUTPUT4
+if [ $? -eq 0 ]; then
+    echo "Test 4 Success"
+else
+    echo "Test 4 Failure"
+fi
+
+diff "Sorted 3.txt" $OUTPUT5
+if [ $? -eq 0 ]; then
+    echo "Test 5 Success"
+else
+    echo "Test 5 Failure"
+fi
+
+diff "Sorted 4.txt" $OUTPUT6
+if [ $? -eq 0 ]; then
+    echo "Test 6 Success"
+else
+    echo "Test 6 Failure"
+fi