Uploading a problem for the exam

exam_problem2.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+
+
+// Sa se genereze un fisier binar cu 100 de numere reale(float/double) arbitrar.
+void generate_file(const char * filename) {
+    srand(time(NULL));
+    FILE * file = fopen(filename, "wb");
+    if ( !file ) {
+        perror("Can't open file!");
+        return;
+    }
+
+    double numbers[100];
+    for (int i = 0; i < 100; ++i) {
+        numbers[i] = rand() % 1000000 / 1000.0;
+    }
+
+    fwrite(numbers, sizeof(double), 100, file);
+    fseek(file, 0, SEEK_SET);
+
+    if ( fclose(file) ) {
+        perror("Can't close file.");
+    }
+}
+
+//Se va citi continutul acestui fisier intr-o lista dublu inlantuita ordonata crescator.
+typedef struct _dl_list * List;
+struct _dl_list {
+    double data;
+    List next;
+    List prev;
+};
+
+List init() {
+    // create dummy list
+    List new_list = malloc(sizeof(struct _dl_list));
+    new_list->data = -1;
+    new_list->next = new_list;
+    new_list->prev = new_list;
+    return new_list;
+}
+
+void add(List list, double data) {
+    List head = list;
+    int flag = 0;
+    while( list->next != head ) { // middle insertion
+        list = list->next;
+        if ( data < list->data && !flag) {
+            List cur_node = list;
+            List node = malloc(sizeof(struct _dl_list));
+            node->data = data;
+            node->next = cur_node;
+            node->prev = cur_node->prev;
+
+            cur_node->prev->next = node;
+            cur_node->next->prev = cur_node;
+            cur_node->prev = node;
+            //  head ... prev node | wwwti | cur node | next node ... last node
+            //                                   ^
+            // wwwti = where we want to insert.
+            flag = 1;
+        }
+    }
+    if ( list == head ) { // first insertion
+        List node = malloc(sizeof(struct _dl_list));
+        node->data = data;
+        node->next = head;
+        node->prev = head;
+        list->next = node;
+        list->prev = node;
+        list = list->next;
+    } if ( list->next == head && data > list->data) { // last insertion
+        // cur_node | wwwti | head
+        //    ^
+        List node = malloc(sizeof(struct _dl_list));
+        node->data = data;
+        node->next = head;
+        node->prev = list;
+
+        list->next = node;
+        list = list->next; // move to wwwti
+    }
+
+    // make list circular.
+    list->next = head;
+    head->prev = list;
+}
+
+void print_list(List list) {
+    List head = list;
+    int counter = 0;
+    int item_counter = 0;
+    while ( list->next != head ) {
+        list = list->next;
+        ++item_counter;
+        // \x1b[31m = color red; %03d; \x1b[0m = color reset;
+        printf("\x1b[31m%03d\x1b[0m: %07.3f ", item_counter, list->data);
+        ++counter;
+        if ( counter % 5 == 0) {
+            printf("\n");
+            counter = 0;
+        }
+    }
+    printf("\n");
+    printf("next %.3f\n", list->next->data); // -1 is dummy value
+    printf("next's prev %.3f\n", list->next->prev->data);
+    printf("prev %.3f\n", list->prev->data);
+    printf("head prev %.3f\n", head->prev->data);
+
+}
+
+void read_from_file(List list, const char * filename) {
+    FILE * file = fopen(filename, "rb");
+    if ( !file ) {
+        perror("Can't open file!");
+        return;
+    }
+
+    double item;
+    while ( fread(&item, sizeof(item), 1, file) != 0) {
+        add(list, item);
+    }
+
+    if ( fclose(file) ) {
+        perror("Can't close file!");
+    }
+}
+
+// Sa se sorteze fisierul binar in ordine descrescatoare si sa se afisieze continutul listei pe ecran.
+// Read the items into a buffer, qsort them, write them to file.
+int comparator(const void * a, const void * b) {
+    double f = *((double *) a);
+    double s = *((double *) b);
+    if ( f > s ) {
+        return -1;
+    } else if ( f < s) {
+        return 1;
+    }
+    return 0;
+}
+
+void sort_file(const char * filename) {
+    FILE * file = fopen(filename, "rb+");
+    if ( !file ) {
+        perror("Can't open file!");
+        return;
+    }
+
+    double items[100];
+    for ( int i = 0; i < 100; ++i ) {
+        fread(&items[i], sizeof(double), 1, file);
+    }
+    qsort(items, sizeof(items)/sizeof(items[0]), sizeof(double), comparator);
+
+    fseek(file, 0, SEEK_SET);
+    for ( int i = 0; i < 100; ++i ) {
+        fwrite(&items[i], sizeof(items[0]), 1, file);
+    }
+
+    if ( fclose(file) ) {
+        perror("Can't close file!");
+    }
+}
+
+int main() {
+
+    generate_file("numbers.txt");
+    List boss = init();
+    read_from_file(boss, "numbers.txt");
+    print_list(boss);
+    sort_file("numbers.txt");
+
+    return 0;
+}