Question

Write a program reverse-order.cpp which asks the user to input two dates (earlier date then later date). The program should report the West basin elevationfor all days in the interval in the reverse chronological order (from the later date to the earlier).

Example:

$ ./reverse-order
Enter earlier date: 05/29/2018
Enter later date: 06/02/2018

06/02/2018  590.22 ft
06/01/2018  590.23 ft
05/31/2018  590.24 ft
05/30/2018  590.26 ft
05/29/2018  590.32 ft

Hint: If for the previous tasks you did not use arrays, here you really have to read the data into arrays first, and only then report them in the required order.

********************************************************************USE THE FORMAT BELOW TO READ THE FILE*******************************

The datafile is a plain text file whose first line is a header followed by rows of data. The entries in each row are separated by the tab symbol, hence the name of the file format: TSV (tab-separated-values). It is the most convenient format for reading by our C++ program.

Each row has five fields: Date, Storage (in billions of gallons) and Elevation (in feet) for the East basin and for the West basin of the reservoir:

Date             EastStorage    EastElevation    WestStorage    WestElevation
01/01/2018          59.94           574             32.67           574.33
01/02/2018          59.89           573.99          32.57           574.29
01/03/2018          59.89           573.97          32.44           574.24
01/04/2018          59.9            573.97          32.22           574.07
...

To read the datafile, we have to open an input file stream (represented by an object of type ifstream, here we called it fin):

ifstream fin("Current_Reservoir_Levels.tsv");
if (fin.fail()) {
    cerr << "File cannot be opened for reading." << endl;
    exit(1); // exit if failed to open the file
}

Remember that the first line in the file is a header line. We have to skip it before we get to process the actual data. We can do that by reading that line into a temporary variable that we can call junk:

string junk;        // new string variable
getline(fin, junk); // read one line from the file 

After that, the file can be read line by line. The most idiomatic C++ way to read such well-formatted file until the end would be the following:

while(fin >> date >> eastSt >> eastEl >> westSt >> westEl) { 
    // this loop reads the file line-by-line
    // extracting 5 values on each iteration 
    
    fin.ignore(INT_MAX, '\n'); //skips to the end of line, 
                          //ignorring the remaining columns 

    // for example, to print the date and East basin storage:
    cout << date << " " << eastSt << endl;
}

Here, variable date can be of type string, and the others are numeric variables of type double extracting the storage and elevation in East and West basins.

Answer 1

Answer : please upvote if its up to your expectation or comment for any query i will update the same. Thanks.

please check output Data and File Data in Attached Image.

Program Plan : Objective is Find West Basin Elevation between Earlier and Later Date from File

1. Get User Input Earlier Date and Later Date

2. Open File or not found error

3. Read Date from File and compare with Earlier and Later Date

4. if Matched print Date and West Basin Elevation else read next Date untill EOF(End of File)

5. Repeat Step 3 to 4.

Program :

#include <iostream>
#include <fstream>
#include <stdlib.h>
#include <string>

using namespace std;

string FindWestElevation(string str,char c); //Find Last occurence of character
int GetMonth(string Date); //get int value of month from date
int GetDay(string Date); //get int value of day from date
int GetYear(string Date); //get int value of day from year

int main()
{

string LaterDate,EarlierDate; //string to save input from user Later ,earlier
cout<<"Enter Earlier Date ";
cin>>EarlierDate;
cout<<"Enter Later Date ";
cin>>LaterDate;

ifstream fin("Current_Reservoir_Levels.tsv"); //open the file
if (fin.fail()) { //if file not found or unable to open throw error and exit
cerr << "File cannot be opened for reading." << endl;
exit(1); // exit if failed to open the file
}
else
{

// new string variable

while(fin)
{

string junk; //first chunk header of file
getline(fin,junk);
int pos=junk.find(" "); //find date ->parse using space
string date=junk.substr(0,pos); //store it in Date which is file Date
int FileMonth=GetMonth(date); //Int value
int FileDay=GetDay(date); //Int value
int FileYear=GetYear(date); //Int value

// cout<<"FileDate"<<FileMonth<<" "<<FileDay<<" "<<FileYear<<endl;

int EarlierMonth=GetMonth(EarlierDate); //Int Value of Eariler Date
int EarlierDay=GetDay(EarlierDate);
int EarlierYear=GetYear(EarlierDate);

// cout<<"EarilerDate"<<EarlierMonth<<" "<<EarlierDay<<" "<<EarlierYear<<endl;

int LaterMonth=GetMonth(LaterDate); //Int value of Later Date
int LaterDay=GetDay(LaterDate);
int LaterYear=GetYear(LaterDate);

// cout<<"LaterDate"<<LaterMonth<<" "<<LaterDay<<" "<<LaterYear<<endl;
if((FileMonth>=EarlierMonth) && (FileDay>=EarlierDay) && (FileYear>=EarlierYear)) //File Date greater than or equal to file Date
{
if((FileMonth<=LaterMonth) && (FileDay<=LaterDay) && (FileYear<=LaterYear)) //File Date less than or equal to File Date
{

cout<<date<<" "; //if true print Date
string WestElevation=FindWestElevation(junk,' '); //Find West Elevation
cout<<WestElevation.append(" ft")<<endl; //append ft and print Data
}
else
{
// cout<<"False1"<<endl;
}
}
else
{
//cout<<"False"<<endl;
}

}

}

}

string FindWestElevation(string str,char c) //return string and find last occurence of character
{

int index = -1;
for (int i = 0; i < str.length(); i++)
{
if (str[i] == c)
index = i;
}

string sub=str.substr(index+1); //get substring from last occurence to end of string

return sub;

}

int GetMonth(string Date)
{
int Month=0;
int pos=Date.find('/'); //first occurence of / charcter
Date=Date.substr(0,pos); //string from 0 to first occurence
Month=atoi(Date.c_str()); //string to const *pointer array and convert to integer

return Month;

}

int GetDay(string Date)
{
int Day=0;
int pos=Date.find('/'); //find first occurence
Date=Date.substr(pos+1);
pos=pos=Date.find('/'); //find second occurence
Date=Date.substr(0,pos);

Day=atoi(Date.c_str()); //

return Day;

}

int GetYear(string Date)
{
string Year =FindWestElevation(Date,'/'); //find last occurence of charcter

int year=atoi(Year.c_str()); //get integer value
return year;

}

Output :