Question

Could you write a c- program that reads a text file into a linked list of characters and then manipulate the linked list by making the following replacements

1. Replace all “c” with “s” if followed by the characters “e”, “i” or “y”; otherwise

2. Replace "sh" with ph

This is the text to be manipulated:

Paragraph1

She told us to take the trash out.

Why did she do that?

I wish she would not do that

Paragraph 2

We came home very late despite the fact we had school the next day.

We had a lot of fun

I miss my friends.

In c programming language please

Answer 1

C code that reads a text file, create a linked list of characters from file then replaces characters as per instructions.

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

typedef struct node {
    char val;
    struct node * next;
} node_t;

void print_list(node_t * head) {
    node_t * current = head;

    while (current != NULL) {
        printf("%c", current->val);
        current = current->next;
    }
}

void push_back(node_t * head, char val) {
    node_t * current = head;
    while (current->next != NULL) {
        current = current->next;
    }

    /* now we can add a new variable */
    current->next = (node_t *) malloc(sizeof(node_t));
    current->next->val = val;
    current->next->next = NULL;
}

void replace_chars(node_t* head) {
    node_t* current = head;
    node_t* prev = head;
    
    if (head != NULL) {
        prev = current;
        current = current->next;
        
        while (current != NULL) {
            if (tolower(current->val) == 's' || tolower(current->val) == 'e' || tolower(current->val) == 'y') {
                if (tolower(prev->val) == 'c') prev->val = (char)((int)prev->val + 16);
            }
            if (tolower(current->val) == 'h' && tolower(prev->val) == 's') prev->val = (char)((int)prev->val - 3);
            prev = current;
            current = current->next;
        }
    }
}

int main() {
    // open file
    FILE *fp;
    fp = fopen("test.txt", "r");
    
    // crate head of linked list
    node_t * head = NULL;
    head = (node_t *) malloc(sizeof(node_t));
    
    // reads single character from file
    char c = fgetc(fp); 
    head->val = c;
    
    // run this while loop till we reach EOF (end of file)
    while (c != EOF) {
        // read a character
        c = fgetc(fp);
        // add latest character to end of linked list
        if (c != EOF) push_back(head, c);
    }
    
    replace_chars(head);
    
    print_list(head);
    
    return 0;
}

File - test.txt

Output:

Please refer this screenshot for indentation help:

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