Insertion Sort

InsertionSort.cpp

// InsertionSort.cpp : Defines the entry point for the console application.
// input.txt file should be here.
// L.D.C.Lakmal

#include "stdafx.h"
#include <stdio.h>
#include <iostream>
#include <fstream>

using namespace std;

#define ARRAY_SIZE 1000
#define LINE_LENGTH ARRAY_SIZE*10

int read_input_array(char* fileName, int* inputArray);
void insertion_sort(int inputSize, int* inputArray);
void display_array(int size, int* intArrray);

int main(int argc, char* argv[])
{
	int myArray[ARRAY_SIZE];
	int numElements = 0;
	char* fileName;
	if(argc == 2){
		fileName = argv[1];
	}
	else{
		cout << "Incorrect number of arguments! Input file name is required. Number of arguments received is " << argc-1 << ".\n";
		system("pause");
		exit(-1);
	}
	
	numElements = read_input_array(fileName, myArray);
	if(numElements < 0){
		cout << "Error in reading input.\n";
		system("pause");
		exit(-1);
	}
	display_array(numElements, myArray);

	insertion_sort(numElements, myArray);
	display_array(numElements, myArray);
	
	system("PAUSE");
	return 0;
}

/*
 * This method will read the inputs from the file specified by the parameter fileName.
 * The first line of the file contains the number of elements in the array.
 * The second line of the array contains the numbers.
 * Parameter inputArray is the array to which the umbers will be saved.
 * The method will return the number of items read in case of success. IN case of failure it will return -1.
 */
int read_input_array(char* fileName, int* inputArray){
	ifstream inFile;
	//Open File
	inFile.open(fileName);
	//Check for errors in opeing file
	if (inFile.fail()) {
		cerr << "unable to open file " << fileName <<" for reading\n";
		inFile.close();
		system("pause");
		return -1;
	}
	int n;
	char currentLine[LINE_LENGTH];
	//Read first line
	if(!inFile.eof())
		inFile.getline(currentLine,sizeof(currentLine));
	else{
		cout << "Error in reading first line!\n";
		inFile.close();
		return -1;
	}
	//Convert it to number of elements
	n = atoi(currentLine);

	//Read second line
	if(!inFile.eof())
		inFile.getline(currentLine,sizeof(currentLine));
	else{
		cout << "Error in reading second line!\n";
		inFile.close();
		return -1;
	}
	inFile.close();
	
	//Split line into numbers and convert them to 
	char* number_string;
	char delimiters[] = " ,.";
	number_string = strtok(currentLine, delimiters);
	int i = 0;
	while(number_string != NULL && i<n){
		inputArray[i] = atoi(number_string);
		if(inputArray[i] == 0){
			cout << "Error! Invalid Input: The input " <<i+1 <<" (" << number_string <<")is either zero or not a number!\n";
			return -1;
		}
		i++;
		number_string = strtok(NULL, delimiters);
	}
	if(number_string != NULL){
		cout <<"Warning: Some inputs ignored!\n";
	}
	//Check whether the required number of integers were read.
	if (i<n){
		cout << "Error! Required number of values not fund in line 2! n is " <<n <<" and number of values read (i) is " <<i <<endl;
		return -1;
	}
	return n;
}

void insertion_sort(int inputSize, int* inputArray){
	//Implement Insertion Sort Here
	for(int i=1; i<inputSize; i++){
		int key = inputArray[i];
		int j = i-1;
		while (j>=0 && inputArray[j]>key){
			inputArray[j+1] = inputArray[j];
			j = j-1;
		}
		inputArray[j+1] = key;
	}
}

void display_array(int size, int* intArray){
	cout << "Displaying Array: ";
	cout << "\tArray Size: " << size << "  - Elements: ";
	for(int i=0; i<size; i++){
		cout << intArray[i];
		if(i < size-1)
			cout <<", ";
		else
			cout <<"\n";
	}
}