I am working on an assignment that deals with file input and output. The instructions are as follows:
Write a program to update an inventory file. Each line of the inventory file will have a product number, a product name and a quantity separated by vertical bars. The transaction file will contain a product number and a change amount, which may be positive for an increase or negative for a decrease. Use the transaction file to update the inventory file, writing a new inventory file with the update quantities. I have provided 2 Input files to test your program with as well as a sample output file so you see what it should look like when you are done.
Hints:
This program requires 3 files
Initial Inventory File
File showing updates to be made
New Inventory File with changes completed
Use Lists to capture the data so you don’t have to worry about the number of items in the files
Each line of the Inventory file looks something like this:
123 | television | 17
I have also been given the basic structure and outline of the program:
class Program
{
public class InventoryNode
{
// Create variables to hold the 3 elements of each item that you will read from the file
// Make them all public
public InventoryNode()
{
// Create a constructor that sets all 3 of the items to default values
}
public InventoryNode(int ID, string InvName, int Number)
{
// Create a constructor that sets all 3 of the items to values that are passed in
}
public override string ToString() // This one is a freebie
{
return IDNumber + " | " + Name + " | " + Quantity;
}
}
static void Main(String[] args)
{
// Create variables to hold the 3 elements of each item that you will read from the file
// Create variables for all 3 files (2 for READ, 1 for WRITE)
List<InventoryNode> Inventory = new List<InventoryNode>();
InventoryNode Item = null;
// Create any other variables that you need to complete the work
// Check for proper number of arguments
// If there are not enough arguments, give an error message and return from the program
// Otherwise
// Open Output File
// Open Inventory File (monitor for exceptions)
// Open Update File (monitor for exceptions)
// Read contents of Inventory into the Inventory List
// Read each item from the Update File and process the data
// Write output file
//Close all files
return;
}
}
There is a lot of steps to this problem but right now I am only really concerned with how to read the inventory file into a list. I have read files into arrays before, so I thought I could do that and then convert the array to a list. But I am not entirely sure how to do that. Below is what I have created to add to the main method of the structure above.
int ID;
string InvName;
int Number;
string line;
List<InventoryNode> Inventory = new List<InventoryNode>();
InventoryNode Item = null;
StreamReader f1 = new StreamReader(args[0]);
StreamReader f2 = new StreamReader(args[1]);
StreamWriter p = new StreamWriter(args[2]);
// Read each item from the Update File and process the data
while ((line = f1.ReadLine()) != null)
{
string[] currentLine = line.Split('|');
{
ID = Convert.ToInt16(currentLine[0]);
InvName = currentLine[1];
Number = Convert.ToInt16(currentLine[2]);
}
}
I am a bit hung up on the Inventory Node Item = null; line. I am not really sure what this is supposed to be doing. I really just want to read the file to an array so I can parse it and then pass that data to a list. Is there a way to do that that is something similar to the block I have written? Maybe there is a simpler way. I am open to that, but I figured I'd show my train of thought.
There is not need to add everything to an array and then convert it to the list. InventoryNode Item = null is there to represent a line from the file.
You're pretty close. You just need to instantiate the InventoryNode and feed it the results of the split() method.
You're almost there. You already have fetched ID, InvName and Number, so you just have to instantiate the InventoryNode:
Item = new InventoryNode(...);
And then add Item to your list.
Note that Inventory Node Item = null; is not doing much; it just declares a variable that you can use later. This wasn't strictly necessary as the variable could have been declared inside the loop instead.
Related
Well, I'm facing an issue on exporting my data to SQL Server as the subject says.
I have a semicolon delimited file, but also I have occurrences when I find semicolon inside the text, for example:
ID;DESCRIPTION;VALUE
1;TEXT1;35
2;TEXT;2;45
3;TE;XT3;50
So as you can see I have some garbage that I would like to remove, since this is shifting the columns.
I have some ideas, like make a standard count of semicolons, in this case it would be 2 semicolons by line and remove the extra ones.
In my case this is always happening in 1 column specifically the Address column and complement, so i know exactly what the number of the column is.
I cant ask people who dispose this file since the system is an old system and they can't put qualifiers like double quotes or simply change the delimiter.
I know I could do this via script task but I have few knowledge on programming, so I'm trying to look for another manner.
I'd like to say again that this problem is happening on source file so when I configure the flat file connection it already shift the column so I can't make any treatment like derived column or something else. I have to do the changes on the file itself before I load it in SSIS.
I've been looking for some days on any kind of forums and I don't see any similar questions and solutions for this problem, since most of the example files of people who asks, already have qualifiers or something like this, so I really appreciate if you can help me!
You mentioned you have little programming knowledge but a script is only solution that can handle delimiters in fields that are not enclosed. You are fortunate there is only a single problem field as it wouldn't be possible to parse ambiguous delimiters unless you have additional rules to determine where actual fields begin and end.
As long as you are certain there is only one field with embedded delimiters, one method is a data flow source Script component. Below are the steps to create one:
Add a script component to data flow and select Source for the type
Add the flat file connection manager to the script properties Connection Managers collection
Add each field as an output column under the script properties component Input and Outputs
Edit the script source and replace the template 'CreateOutputRows()' method code with the version code below.
See comments in the script indicating where customizations are needed for your actual file. This version will work with your sample file of 3 fields, with the second field having embedded delimiters.
public override void CreateNewOutputRows()
{
const char FIELD_DEMIMITER = ';';
////*** change this to the zero-based index of the problem field
const int BAD_FIELD_INDEX = 1;
////*** change this to the connection added to script componenent connection manager
var filePath = this.Connections.FlatFileSource.ConnectionString;
string record = "";
using (var inputFile = new System.IO.StreamReader(filePath))
{
record = inputFile.ReadLine();
if(record != null)
{
//count header record fields to get expected field count for data records
var headerFieldCount = record.Split(FIELD_DEMIMITER).Length;
while (record != null)
{
record = inputFile.ReadLine();
if(record == null)
{
break; //end of file
}
var fields = record.Split(FIELD_DEMIMITER);
var extraFieldCount = fields.Length - headerFieldCount;
if (extraFieldCount < 0)
{
//raise an error if fewer fields that we expect
throw new DataException(string.Format("Invalid record. {0} fields read, {1} fields in header.", fields.Length, headerFieldCount));
}
if (extraFieldCount > 0)
{
var newFields = new string[headerFieldCount];
//copy preceding good fields
for (var i = 0; i < BAD_FIELD_INDEX; ++i)
{
newFields[i] = fields[i];
}
//combine segments of bad field into single field
var sourceFieldIndex = BAD_FIELD_INDEX;
var combinedField = new System.Text.StringBuilder();
while (sourceFieldIndex <= extraFieldCount + BAD_FIELD_INDEX)
{
combinedField.Append(fields[sourceFieldIndex]);
if(sourceFieldIndex < extraFieldCount + BAD_FIELD_INDEX)
{
combinedField.Append(FIELD_DEMIMITER); //add delimiter back to field value
}
++sourceFieldIndex;
}
newFields[BAD_FIELD_INDEX] = combinedField.ToString();
//copy subsquent good fields
var targetFieldIndex = BAD_FIELD_INDEX + 1;
while (sourceFieldIndex < fields.Length)
{
newFields[targetFieldIndex] = fields[sourceFieldIndex];
++sourceFieldIndex;
++targetFieldIndex;
}
fields = newFields;
}
//create output record and copy fields
this.Output0Buffer.AddRow();
//*** change the code below to map source fields to the columns defined as script component output
Output0Buffer.ID = fields[0];
Output0Buffer.DESCRIPTION = fields[1];
Output0Buffer.VALUE = fields[2];
}
}
}
this.Output0Buffer.SetEndOfRowset();
}
Another thing you can do is import the text file into a single column (varchar(max)) staging table, and then use TSQL to parse the records and import them to your final destination table.
Some background about my code, I basically have a record class which has a lot of properties to capture the required data provided in the form of .txt files and each column is divided into their own separate files i.e. Month.txt, Day.txt, containing 600 rows of data in each.
Now, I have a second array which is basically a collection of the aforementioned class and I give it max value of 600 (as there are 600 of data). This class possesses an Initialization method.
This way it Initializes my records each column at the time, but I have to know the fixed size of the rows to not run into index out of range exception. Also, I have a lot of properties so the overall "if else" statements make this code look very redundant and hard on the eye. Flexibility is also an issue as the point resets to 0, so when I want to add extra data, I will just be overriding the original 600.
Is there anyway to improve this?
The code is suboptimal, because it checks the file name for each line in that file. It is better to decide what field to set before the loop, and then use that decision throughout the loop.
First, make a look-up table of setters based on the file prefix:
var setters = new Dictionary<string,Action<Record,string>> {
["Day"] = (r,v) => r.Day = v
, ["Month"] = (r,v) => r.Month = v
, ...
};
With this look-up in place, the reading code becomes straightforward:
using (StreamReader R = new StreamReader(file.FullName)) {
var pos = File.Name.IndexOf("_");
Action<Record,string> fieldSetter;
if (pos < 0 || !setters.TryGetValue(File.Name.Substring(0, pos), out fieldSetter)) {
continue; // Go to next file
}
string temp;
while((temp = R.ReadLine()) != null) {
fieldSetter(records[pointer++], temp);
}
}
First, we look up the setter using the prefix from the file name up to the first underscore character '_'. Then we go through the lines from the file, and call that setter for each record passing the string that we got.
Adding new fields becomes simple, too, because all you need is to add a new line to the setters initializer.
I'm trying to complete an assignment and I'm having trouble with the following (I have worked on this for the last 12 hours). Please help.
I have opened a file, saved the file into an struct array. Can access each element of the struct but don't know how I can access each individual field. i.e
Struct
//struct to hold the hand values
public struct CurrentHand
{
public char cardSuit;
public int cardValue;
}
I need to extract the cardValue into an array or variables so I can evaluate each record i.e. is the hand a pair or two pair etc. I have no idea how to do this. From what I have found its not possible to access each field, is this true?
//Open file and load data into array
public static void LoadHandData(CurrentHand[] handData, string fileName)
{
string input = ""; //temporary variable to hold one line of data
string[] cardData; //temporary array to hold data split from input
//Open the file and read the contents
StreamReader readHand = new StreamReader(fileName);
input = readHand.ReadLine(); //one record
cardData = input.Split(' '); //split record into fields
for (int counter = 0; counter < handData.Length; counter++)
{
handData[counter].cardSuit = Convert.ToChar(cardData[counter *2]);
handData[counter].cardValue = Convert.ToInt16(cardData[counter *2 +1]);
}
readHand.Close();
}
To obtain an array containing the values of the cards you hold in your hand, you can do:
var values = handData.Select(x=>x.cardValue).ToArray();
var seeds = handData.Select(x=>x.cardSuit).ToArray();
By the way, your struct should be called Card or something like that, since an Hand is supposed to be a collection of cards. The name you gave to it is just confusing and makes your code less readeable.
Your problem is not clear to me. anyway you can access invidual fields using .
try this...
CurrentHand.cardValue
using above you can get and set value for CurrentHand structure.
I need to merge two files while also applying a sort. It is important the I keep the task light on memory usage. I need to create a console app in c# for this.
Input File 1:
Some Header
A12345334
A00123445
A44566555
B55677
B55683
B66489
record count: 6
Input File 2:
Some Header
A00123465
B99423445
record count: 2
So, I need to make sure that the third file should have all the "A" records coming first and then the "B" records followed by the Total record count.
Output File:
Some header
A12345334
A00123445
A44566555
A00123465
B99423445
B55677
B55683
B66489
record count: 8
Record sorting within "A" and "B" is not relevant.
Since your source files appear sorted, you can do with with very low memory usage.
Just open both input files as well as a new file for writing. Then compare the next available line from each input file and write the line that comes first to your output file. Each time you write a line to the output file, get the next line from the input file it came from.
Continue until both input files are finished.
If memory is an issue the easiest way to do this is probably going to be to read the records from both files, store them in a SQLite or SQL Server Compact database, and execute a SELECT query that returns a sorted record set. Make sure you have an index on the field you want to sort on.
That way, you don't have to store the records in memory, and you don't need any sorting algorithms; the database will store the records on disk and do your sorting for you.
Quick idea, assuming the records are already sorted in the original files:
Start looping through file 2, collecting all A-records
Once you reach the first B-record, start collecting those in a separate collection.
Read all of File 1.
Write out the content of the A-records collection from file 2, then append the contents read from file 1, followed by the B-records from file 2.
Visualized:
<A-data from file 2>
<A-data, followed by B-data from file 1>
<B-data from file 2>
If you are concerned about memory this is a perfect case for insertion sort and read one line at a time from each file. If that is not an issue read the whole thing into a list and just call sort the write it out.
If you can't even keep the whole sorted list in memory then a database or memory mapped file is you best bet.
Assuming your input files are already ordered:
Open Input files 1 and 2 and create the Output file.
Read the first record from file 1. If it starts with A, write it to the output file. Continue reading from input file 1 until you reach a record that starts with B.
Read the first record from file 2. If it start with A, write it to the output file. Continue reading from input file 2 until you reach a record that starts with B.
Go back to file 1, and write the 'B' record to the output file. Continue reading from input file 1 until you reach the end of the stream.
Go back to file 2, and write the 'B' record to the output file. Continue reading from input file 2 until you reach the end of the stream.
This method will prevent you from ever having to hold more than 2 rows of data in memory at a time.
i would recommend using StreamReader and StreamWriter for this application. So you can open a file using StreamWriter, copy all lines using StreamReader for file #1, then for file #2. This operations are very fast, have integrated buffers and are very lightweight.
if the input files are already sorted by A and B, you can switch between the source readers to make the output sorted.
Since you have two sorted sequences you just need to merge the two sequences into a single sequence, in much the same way the second half of the MergeSort algorithm works.
Unfortunately, given the interface that IEnumerable provides, it ends up a bit mess and copy-pasty, but it should perform quite well and use a very small memory footprint:
public class Wrapper<T>
{
public T Value { get; set; }
}
public static IEnumerable<T> Merge<T>(IEnumerable<T> first, IEnumerable<T> second, IComparer<T> comparer = null)
{
comparer = comparer ?? Comparer<T>.Default;
using (var secondIterator = second.GetEnumerator())
{
Wrapper<T> secondItem = null; //when the wrapper is null there are no more items in the second sequence
if (secondIterator.MoveNext())
secondItem = new Wrapper<T>() { Value = secondIterator.Current };
foreach (var firstItem in first)
{
if (secondItem != null)
{
while (comparer.Compare(firstItem, secondItem.Value) > 0)
{
yield return secondItem.Value;
if (secondIterator.MoveNext())
secondItem.Value = secondIterator.Current;
else
secondItem = null;
}
}
yield return firstItem;
yield return secondItem.Value;
while (secondIterator.MoveNext())
yield return secondIterator.Current;
}
}
}
Once you have a Merge function it's pretty trivial:
File.WriteAllLines("output.txt",
Merge(File.ReadLines("File1.txt"), File.ReadLines("File2.txt")))
The File ReadLines and WriteAllLines here each utilize IEnumerable and will stream the lines accordingly.
Here's the source code for the more generic/boiler plate solution for merge sorting 2 files.
public static void Merge(string inFile1, string inFile2, string outFile)
{
string line1 = null;
string line2 = null;
using (StreamReader sr1 = new StreamReader(inFile1))
{
using (StreamReader sr2 = new StreamReader(inFile2))
{
using (StreamWriter sw = new StreamWriter(outFile))
{
line1 = sr1.ReadLine();
line2 = sr2.ReadLine();
while(line1 != null && line2 != null)
{
// your comparison function here
// ex: (line1[0] < line2[0])
if(line1 < line2)
{
sw.WriteLine(line1);
line1 = sr1.ReadLine();
}
else
{
sw.WriteLine(line2);
line2 = sr2.ReadLine();
}
}
while(line1 != null)
{
sw.WriteLine(line1);
line1 = sr1.ReadLine();
}
while(line2 != null)
{
sw.WriteLine(line2);
line2 = sr2.ReadLine();
}
}
}
}
}
public void merge_click(Object sender, EventArgs e)
{
DataTable dt = new DataTable();
dt.Clear();
dt.Columns.Add("Name");
dt.Columns.Add("designation");
dt.Columns.Add("age");
dt.Columns.Add("year");
string[] lines = File.ReadAllLines(#"C:\Users\user1\Desktop\text1.txt", Encoding.UTF8);
string[] lines1 = File.ReadAllLines(#"C:\Users\user2\Desktop\text1.txt", Encoding.UTF8);
foreach (string line in lines)
{
string[] values = line.Split(',');
DataRow dr = dt.NewRow();
dr["Name"] = values[0].ToString();
dr["designation"] = values[1].ToString();
dr["age"] = values[2].ToString();
dr["year"] = values[3].ToString();
dt.Rows.Add(dr);
}
foreach (string line in lines1)
{
string[] values = line.Split(',');
DataRow dr = dt.NewRow();
dr["Name"] = values[0].ToString();
dr["designation"] = values[1].ToString();
dr["age"] = values[2].ToString();
dr["year"] = values[3].ToString();
dt.Rows.Add(dr);
}
grdstudents.DataSource = dt;
grdstudents.DataBind();
}
I'm making a program in C# that uses mathematical sets of numbers. I've defined the class Conjunto (which means "set" in spanish). Conjunto has an ArrayList that contains all the numbers of the set. It also has a string called "ID" which is pretty much what it sounds; the name of an instance of Conjunto.
The program have methods that applies the operations of union, intersection, etc, between the sets.
Everything was fine, but now i've a text file with sentences like:
A={1,2,3}
B={2,4,5}
A intersection B
B union A
And so on. The thing is, i don't know how many sets the text file contains, and i don't know how to name the variables after those sentences. For example, name an instance of Conjunto A, and name another instance B.
Sorry for the grammar, english is not my native language.
Thanks!
It's pretty complicated to create varaibles dynamically, and pretty useless unless you have some already existing code that expects certain variables.
Use a Dictionary<string, Conjunto> to hold your instances of the class. That way you can access them by name.
First off, If you don't target lower version than .Net 2.0 use List instead of ArrayList. If I were you I wouldn't reinvent the wheel. Use HashSet or SortedSet to store the numbers and then you can use defined union and intersection.
Secondly, what is your goal? Do want to have just the output set after all operations? Do you want to read and store all actions and them process it on some event?
First of all, your program is taken from bad side. I would advice to start making new one. One of ways to name "variables" dynamicaly is by making class objects and editing their properties.
This is what I made as a starting platform:
First af all I have crated a class called set
class set
{
public string ID { get; set; }
public List<int> numbers { get; set; }
}
Then I have made the code to sort whole textfile into list of those classes:
List<set> Sets = new List<set>();
string textfile = "your text file";
char[] spliter = new char[] { ',' }; //switch that , to whatever you want but this will split whole textfile into fragments of sets
List<string> files = textfile.Split(spliter).ToList<string>();
int i = 1;
foreach (string file in files)
{
set set = new set();
set.ID = i.ToString();
char[] secondspliter = new char[] { ',' }; //switch that , to whatever you want but this will split one set into lone numbers
List<string> data = textfile.Split(secondspliter).ToList<string>();
foreach (string number in data)
{
bool success = Int32.TryParse(number, out int outcome);
if (success)
{
set.numbers.Add(outcome);
}
}
i++;
Sets.Add(set);
}
Hope it helps someone.