Question

This is a C++ question

we do not use namespace std at the beginning of the program

9. Arrays: Functions and Reading From File

Although this code is a little long, the strategy is straightforward and it will really help you practice functions. I have provided a large amount of detail to help you out. In a nutshell, you're going to read some numbers from a file (into an array) and then ask the user for a number that will be used to modify the array values via multiplication. You will need THREE functions:

• Function #1 - Read the numbers from easy-numbers.txt into an array. This file has been included in your Mimir starter code. It is simply the numbers 1 thru 10.
• Function #2 - Modify the array based on the user's multiplier. Example: If the user types 2, you will multiply each number in the array by 2. Instead of 1,2,3... the array will now hold 2,4,6...
• Function #3 - Print all values in the array

So what does main() have? It will call the function that reads the numbers from the file, output the introductory message, and then ask the user for a number two times. After the user provides a number, it must call the appropriate functions to manipulate the array and output the result of that manipulation.

Output:

This program will alter a list of numbers based on your two desired multipliers.
Enter the first multiplier: [user types: 3]

3 6 9 12 15 18 21 24 27 30
Enter the second multiplier: [user types: 2]

6 12 18 24 30 36 42 48 54 60

Notes and Hints:

1) Yes, the user's input must be passed from main() to one of the functions in order for it to work

2) Although I only asked for three functions that focus on arrays, you are welcome to place the user's input in its own function. Use those Chp 6 skills!

The file called easy-numbers.txt contains

1
2
3
4
5
6
7
8
9
10

Answer 1

#include<iostream>
#include<fstream>
#include <bits/stdc++.h>

using namespace std;

int readDataFromFile(string fileName);
void multiplyArray(int arr[], int size, int multiplier);
void printArray(int arr[], int size);

int data[INT_MAX]; //declare an array of maximum size to assign data from file

int main() {
   string filePath = "easy-numbers.txt"; //This the path of file to read data from
   int size,multiplier;
  
   size = readDataFromFile(filePath);  
  
   if(size==0) {
       return 0; //if no data found from the file then exit
   }
  
   cout<<"Enter the first multiplier: ";
   cin>>multiplier; //first user input
   multiplyArray(data, size, multiplier);
   printArray(data, size);
  
   cout<<"\nEnter the second multiplier: ";
   cin>>multiplier; //second user input  
   multiplyArray(data, size, multiplier);
   printArray(data, size);
}

//This method takes filepath as argument
//read data from the file and assign data to the array
//return size of the array
int readDataFromFile(string filePath) {
   ifstream infile;
   infile.open(filePath.c_str()); //oprn file to read
  
   if(!infile.is_open()) { //return zero if file not found
       cout<<"Unable to read the file: "<<filePath;
       return 0;
   }
   int a;
   int index = 0;
   while(infile >> a) { //read data from file and assign value to a
       data[index] = a; //assign read value to array
       index++;
   }
   infile.close(); //close the file
   return index; //returns the number of elements added to the array
}

//This methid takes a array, size of array, multiplers value as argument
//multiplies each element of arrr=ay by multiplier value
void multiplyArray(int arr[], int size, int multiplier) {
   int i;
   for(i=0; i<size; i++) { //multiple each element of array by the "multiplier" value
       arr[i]*=multiplier;
   }
}

//This method takes array, size of the array as input
//print content of the array
void printArray(int arr[], int size) {
   int i;
   for(i=0;i<size;i++) { //read the array and print its value
       cout<<data[i]<<" ";
   }
}