Write a new program called Lab7D that will read strings from a text file and turn them into "encrypted code". Create a bool function called isVowel that accepts a character as a parameter and returns a true if it’s a vowel (aeiou) and false otherwise.

I am writing a C program for the first part and Python program for the second part of the question.    

#include <stdio.h>  //to use input output functions

#include <stdlib.h>  // used here to access exit function

void main() {  //start of the main() function body

char fname[100], character;

// fname is the name of the input file which contains characters and character //variable is used to store characters

FILE *original, *temporary;  

/* two pointers of File type: original is used for the original input file and temporary is used for a temporary file name aux.txt */

printf("Enter the name of the text file to encrypt : ");

//prompts the user to enter the name of the file to be encrypted

scanf("%s",fname);//reads the name of the file from user

original=fopen(fname, "r"); //open the input file in read mode

if(original==NULL)  {

//displays the following message if the file is empty or does not exists

 printf("Cannot open original file");  

 exit(1);  }  //program exits

temporary=fopen("aux.txt", "w");

//creates a temporary file named aux.txt and open that file in write mode

if(temporary==NULL)  { //if temporary file could not be created

 printf("Cannot create a temporary file");

 fclose(original); //closes the original input file

 exit(2);  }  //program exits

while(1)  {

 character=fgetc(original);  

/*pointer original moves through the input file and gets input from original input file one character at a time and store it in character variable */

 if(character==EOF)  

//when all characters are obtained and pointer is at end of file  {

 break;  //the loop breaks }

 else  {  //if EOF is not yet reached

 character=character+100;  

//add 100 to each character to encrypt the characters

 fputc(character, temporary);

 // fputc() writes a single character at a time to aux file }}

fclose(original);  //closes input file

fclose(temporary); //closes aux file

original=fopen(fname, "w");  //opens input file in write mode

if(original==NULL) { //if file does not exist display following message

 printf("Cannot open the original file to write");

 exit(3);  } //program exits

temporary=fopen("aux.txt", "r"); //open aux.txt file in read mode

if(temporary==NULL)  { //if pointer temporary is NULL

 printf(" Cannot open temporary file to read");

 fclose(original);  //closes input file

 exit(4);  } //program exits

while(1)  {

 character=fgetc(temporary);

//obtains every character from aux file pointed by temporary

 if(character==EOF)  //if end of file is reaced {

 break;  } //the loop breaks

 else  { //if end of file is not reached

 fputc(character, original);  

//puts every character to input file }  }

printf(" %s is encrypted \n", fname);  

//displays this message when input file is successfully encrypted

//closes input and aux text files

fclose(original);

fclose(temporary); }  

Explanation:

The program first asks the user to enter the name of the file. Then the program uses two pointers original for input file and temporary for aux text file. It first opens the file whose name is entered by the user and reads that file by getting each single character using fgetc() until the pointer reaches the end of the file. While reading each character of the input file, it encrypts every character using and puts that encrypted content in temporary file names aux.txt using fputc() until the pointer reaches the end of the file. Lastly all the encrypted strings of the are placed in the original input text file.

# bool function that accepts character as parameter and returns true if its a #vowel and false otherwise

def isVowel(character):  

   if character.lower() in 'aeiou':  #converts uppercase char to lowercase

       return True  #return true if character is a vowel    

   else:

       return False #returns false if input character is not a vowel

The program has a function isVowel() which takes a character as a parameter to check if that character is a vowel. If character is in uppercase  letters, it handles these characters using lower() method to convert the character to lowercase and then returns true if that character is a vowel otherwise returns false. To check the working of the function you can replace True and False with print statement such as:

if character.lower() in 'aeiou':

       print("It is a vowel")

   else:

       print("It is not a vowel")

And after that you can call this function and pass a character to it as:

isVowel('i')