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Hi Everyone, I got a question,
I am very much fond of using
string fileContent = File.ReadAllText(fileName)
to read a file. But I found many programmers are using
StreamReader objReader = new StreamReader(fileName);
string fileContent = objReader.ReadToEnd();
objReader.Close();
So, my question, which option is better ? I mean, in what case, I should prefer to use StreamReader over File.ReadAllText() ?
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File.ReadAllText internally makes use of a StreamReader, and is implemented like this:
public static string ReadAllText(string path, Encoding encoding)
{
using (StreamReader reader = new StreamReader(path, encoding))
{
return reader.ReadToEnd();
}
}
So the only real benefit is that it wraps the stream in a using statement and makes for simpler/smaller code.Scott Dorman Microsoft® MVP - Visual C# | MCPD
President - Tampa Bay IASA
[ Blog][ Articles][ Forum Guidelines]
Hey, hey, hey. Don't be mean. We don't have to be mean because, remember, no matter where you go, there you are. - Buckaroo Banzai
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Hi Scott,
Thanks for your answer. I see, I did not know that ReadAllText just wraps the StreamReader. So, I can say that, instead of using ReadAllText, it is MORE EFFICIENT to use the StreamReader Directly, because, I can save a function call (1 Stack Operation) by embedding the code block in my codes, Right ?
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That is ridiculous; reading the whole text file will takes orders of magnitude more cycles than performing a single method call, and hence the latter is completely irrelevant.
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| To add to what Luc said, a single method call is pretty much irrelevant in the context of a ReadToEnd, but the fact that the wrapper includes the "using" statement to clean up resources isn't. It is too easy to forget that the resources are not immediately freed if you use the stream directly, so if you are reading multiple files, then ReadAllText can result in easier to read code that actually works better and more efficiently despite the additional method call! You should never use standby on an elephant. It always crashes when you lift the ears. - Mark Wallace
C/C++ (I dont see a huge difference between them, and the 'benefits' of C++ are questionable, who needs inheritance when you have copy and paste) - fat_boy
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You're welcome. I think others have pretty much answered this question, but...
The "cost" of the extra method call is negligible, particularly when compared to the readability and safety concerns (it is entirely too easy to not properly wrap the StreamReader in a using statement.
That being said, you do need to consider the size of the file you are reading. Larger files will consume more memory in order to store the entire contents as a string. When C# 4 comes out, you can use the File.ReadLines method, which essentially does the same thing as ReadAllText or ReadAllLines except it returns an IEnumrable<string;>.Scott Dorman Microsoft® MVP - Visual C# | MCPD
President - Tampa Bay IASA
[ Blog][ Articles][ Forum Guidelines]
Hey, hey, hey. Don't be mean. We don't have to be mean because, remember, no matter where you go, there you are. - Buckaroo Banzai
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Hi,
ReadAllText and ReadToEnd are very similar.
the real question you should ask yourself is (assuming file size is significant): do I need all data in memory at once? If you do, use ReadAllText; otherwise, use a loop based on StreamReader.ReadLine
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Hi Luc,
Thanks for your answer. So, looks like, ReadAllText is the one I will need as I never found reading part of the file applicable in my whole 10 years programming life, lol If I need to extract some information from a file, I use to Read the whole file and then, use REGEX to get particular information.
Thanks again.
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That is the easy way out, storing all text potentially takes a lot of memory, and Regex is a powerful (i.e. compact) but most often in no way the fastest way to search something. But hey, if that fits your situation, go ahead!
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I prefer a StreamReader in most cases.
You can look at it this way:
The StreamReader is the more general tool and can be used even where the ReadAllText will work.
But ReadAllText may not work in all cases where the StreamReader will.
If you master only one, make it StreamReader.
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Hmm. I need if, I occasionally need goto, and I can build a loop using if and goto; I can't build a general jump out of a for. So I should master goto and forget about for?
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Yes. But that's because you'll be using Assembly.  For/while are just syntactic sugar anyway.
But, come to think of it, I learned programming in BASIC and I did learn loops with goto and then advanced to for and didn't get while until I learned Pascal. This served me well when using DCL which has goto but not for/while/etc. A programmer who knows for/while but not how to create them with goto is stunted.
I'm a big proponent of learning the history of programming, not just the latest hot language. If I ever teach programming I hope to impart this background knowledge to the students.
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yes, I did my share of assembly programming. What impressed me most was IBM 360 having an assembly instruction almost equivalent to a printf() statement.
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Luc Pattyn wrote: IBM 360 ... printf()
Which came first?
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Ritchie was still reading up on Thompson's B language when IBM launched its System/360.
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I want to print my search result or save it showing in the data grid view.how I could do this?
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For the printing I'm out. It's very hard(lots of work) to make a professional printing.
For saving there are lots of ansewers. You could save it to a *.CSV file. Or to Excel or pdf.
For excel this article is all about exporting and formatting the datas from the grid view.
For PDF this one.
And of course many other options.
[Edit]When it comes to printing I always rely on external programs like Excel or
FoxItReader/AcrobatReader or... . I found it easier to create small utilities that export a datagrid or a List<T> or... to Excel or PDF or ... than creating a printing solution.
Sure it takes some time o create the *.dll(s) responsible for the generic export but after words you just call .Export() and you're done.
[/Edit]
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Hi Everybody
I am a freelancer , currently programming a billing management program in my native
language Hindi , I am searching for my technical doubt asking to everybody but till
now not yet answered . The problem is
I have to bill the client who purchases the product the problem is that i have to control
the paper volume of the bill being printed ie) if the client purchases 3 products i have to bill in the
desired language the product and pricings such that the paper volume printed is limitted
by the size of the printed matter (here 3 lines for 3 products) so that it can be teared off the printer is panasonic
dot matrix type panasonic KX-P1121 , here i am printing in hindi how can it be done ??
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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Printing;
namespace WindowsApplication9
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
PaperSize psize;
private void button1_Click(object sender, EventArgs e)
{
printDialog1.Document = printDocument1;
if (printDialog1.ShowDialog() == DialogResult.OK)
{
printDocument1.Print();
}
}
private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
{
//e.PageSettings.PaperSize = psize;
e.Graphics.DrawString("Welcome to C#", new Font("arial",10,FontStyle.Regular), Brushes.Red, 0, 0);
}
private void printDocument1_QueryPageSettings(object sender, QueryPageSettingsEventArgs e)
{
psize = new PaperSize("saurabh", 1000, 400);
e.PageSettings.PaperSize = psize;
}
private void button2_Click(object sender, EventArgs e)
{
PrintPreviewDialog prv = new PrintPreviewDialog();
prv.Document = printDocument1;
prv.Show();
}
}
}
//Set the Custom Paper Size of Ur printer as follows:
//Width=10;
//Height=4;
//Hope this will solve ur problem if ur problem gets solved by this code let me know
saurabh kumar
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Hi
Hope you are Doing well
Thanks for your interest in my question but it seems that there is a problem
How do i know my paper size ; this is the problem !!!
I mean the paper height , suppose a customer "A" purchases 3 products , then i want to print the bill using the dot matrix printer such that the print bill is of 3 lines and paper must stop ejecting after that 3 lines
and
Another customer "B" purchases 18 products , then i want to print the bill using the dot matrix printer such that the print bill is of 18 lines and paper must stop ejecting after that 18 lines
Hope you got the problem , and i need a solution for this , also i need to print in my language hindi (custom font) currently i am doing is writing the bill to a file html and loading it to the webcontrol and printing...
With regards
Winmass
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