lab_assignment_5.c

#include <stdio.h>
#include <stdlib.h>


typedef struct node {
char letter;
struct node* next;
} node;
// Returns number of nodes in the linkedList.
int length(node* head){
    int count = 0;
    node* current = head;
    while (current != NULL) {
        count++;
        current = current->next;
    }
    return count;
}
// parses the string in the linkedList
// if the linked list is head -> |a|->|b|->|c|
// then toCString function wil return "abc"
char* toCString(node* head){
    int len = length(head);
    char* str = (char*)malloc((len + 1) * sizeof(char)); 
    int i = 0;
    node* current = head;
    while (current != NULL) {
        str[i] = current->letter;
        i++;
        current = current->next;
    }
    str[i] = '\0'; 
    return str;
}
// inserts character to the linkedlist
// f the linked list is head -> |a|->|b|->|c|
// then insertChar(&head, 'x') will update the linked list as foolows:
// head -> |a|->|b|->|c|->|x|
void insertChar(node** pHead, char c){
    node* newNode = (node*)malloc(sizeof(node));
    newNode->letter = c;
    newNode->next = NULL;
    if (*pHead == NULL) {
        *pHead = newNode;
    } else {
        node* current = *pHead;
        while (current->next != NULL) {
            current = current->next;
        }
        current->next = newNode; 
    }
}
// deletes all nodes in the linkedList.
void deleteList(node** pHead){
    node* current = *pHead;
    while (current != NULL) {
        node* next = current->next;
        free(current);
        current = next;
    }
    *pHead = NULL;
}
int main(void){
    int i, strLen, numInputs;
    node* head = NULL;
    char* str;
    char c;
    FILE* inFile = fopen("input.txt","r");
    fscanf(inFile, " %d\n", &numInputs);
    while (numInputs-- > 0){
        fscanf(inFile, " %d\n", &strLen);
        for (i = 0; i < strLen; i++){
        fscanf(inFile," %c", &c);
        insertChar(&head, c);
        }
        str = toCString(head);
        printf("String is : %s\n", str);
        free(str);
        deleteList(&head);
        if (head != NULL){
            printf("deleteList is not correct!");
            break;
    }
    }
    fclose(inFile);
}