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

//header file included for standard input output
#include<stdio.h>
//header file included for string operations
#include<string.h>
//header file included for dynamic memory manipulation
#include<stdlib.h>

//structure of node i.e. linked list is defined.
struct node{
    //data for storing char type data
    char data;
    //next pointer points node of same structure type 
    struct node *next;
};

//cFlag to check whether 'c' is followed by the characters 'e', 'i' or 'y'
//initially 0 indicates that 'c' is not followed by the characters 'e', 'i' or 'y'
int cFlag=0;

//pointer to linked list start and last are declared
struct node *start=NULL;
struct node *last=NULL;

//prevChar to store previous character
char prevChar;

//insert() to insert file data into linked list
void insert(char c){
    //temp of node type is dynamically created
    struct node *temp = (struct node *)malloc(sizeof(struct node));

    if(temp==NULL){
        printf("\nMemory Full.");
        return;
    }

    //temp's data is assigned with file's data
    temp->data = c;
    temp->next = NULL;

    //if start is NUll i.e. linked list is empty
    //then make this initial temp node as start and end
    if(start==NULL){
        start = temp;
        last = temp;
        prevChar = c;
        return;
    }

    //cFlag is checked
    if(cFlag==0){
        //if condition satisfied then cFlag will be set to 1
        if((prevChar == 'c') && (c=='e'||c=='i'||c=='y')){
            cFlag = 1;
        }
    }

    
    prevChar = c;

    //file's data are inserted in the linked list's end 
    //so that insertion takes O(1) time to insert data at end of linked list
    last->next = temp;
    last = temp;
}

//processParagraphs() to process the linked list data based on cFlag
void processParagraphs(){
    struct node *temp = start;
    struct node *prev = start;
    //Replace all 'c' with 's' if followed by the characters 'e', 'i' or 'y i.e cFlag=1;
    if(cFlag == 1){
        while(temp!=NULL){
            if(temp->data=='c'){
                temp->data = 's';
            }
            temp = temp->next;
        }
    }
    else{ //otherwise Replace "sh" with ph
        while(temp!=NULL){
            prev = temp;
            temp = temp->next;
            if(temp!=NULL){
                if(prev->data=='s'&&temp->data=='h'){
                    prev->data = 'p';
                }
            }
        }
    }
}

//writeOutput() to generate a output file 
void writeOutput(){
    //filePath where output file is to be stored
    char filePath[20];
    strcpy(filePath,"output.txt");

    //file is opened
    FILE *fileOut = fopen(filePath,"w");
    if(fileOut==NULL){
        printf("\nFile Not Opened Correctly.");
        return;
    }

    //if file is successfully opened
    struct node *temp = start;

    //inserts all data into output file
    while(temp!=NULL){
        fputc(temp->data,fileOut);
        temp = temp->next;
    }

    //closing opened file
    fclose(fileOut);
}

//main() , program execution starts from here
int main(){
    //input file path is set
    char filePath[20];
    strcpy(filePath,"input.txt");

    //input file is opened for reading
    FILE *fileIn = fopen(filePath,"r"); 

    if(fileIn==NULL){
        printf("\nFile Not Opened Correctly.");
        return 0;
    }

    //if file opened successfully

    //ch variable to store characters from file
    char ch;

    //loop iterates till end of file is not reached
    while ((ch = fgetc(fileIn)) != EOF)
    {       
        //insert() is called to insert data into linked list
            insert(ch);
    }

    //input file is closed
    fclose(fileIn);

    //processParagraphs() called to process the linked list based on cFlag
    processParagraphs();

    //writeOutput() called to write in a output file
    writeOutput();

    return 0;
}

Instructions:

1. Must have input.txt file within the same directory upon which the program is going to work.

2.output.txt file will be generated by the program after processing input.txt file.