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Everything he writes is good. I lived that history and it is fascinating. C# (and Java and other "managed" languages) solves a lot of the problems that C++ had where simple coding mistakes could lead to memory leaks and security problems. In C#, a lot of those coding mistakes just won't compile... like this...
if (x = y) {
}
In C++ that was an "assignment and test" all in one line. It assigns the value of y to x and casts the whole expression to boolean, so if y was non-zero, the branch would execute. We almost never did that on purpose, we usually just forgot to say ==(the equality operator) instead of =(the assignment operator). You can still make this mistake in Javascript.
In C# we have to write it this way...
x = y;
if (x != 0) {
}
It forces us to do the assignment and the test separately. This avoids the problem that often we would mistakenly write the first example, when what we meant was a simple test for equality. There's nothing illegal about doing assignment and testing in the same statement, but the C# compiler warns us that it's probably a mistake - you can force it to compile if you really want.
What I'm saying is C# (and Java) is mostly a reaction to C++ and all of the horrible things it would let you do! So, that's why it's helpful to see an example from old languages periodically and an explanation of why we don't do it that way any more, or why we do. In C#, arrays are managed objects, which is a step up from blocks of memory, but that managed object is just insulating you from all the mistakes that were easy to make when you were closer to the block of memory, which is still there, buried beneath objects. I would expect Petzold to cover that - how C++ was dangerous with memory, how we learned all the pitfalls, and built in safeguards right in the language.
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the book I'm reading now sprinkles in comparisons to C++ every now and then… I got in maybe 20 pages into that other book before I realized they both started off pretty similar… That's when I stopped reading it.
There were a few things mentioned in Petzold's e-book that wasn't covered in the book I'm reading now, which is why am going to eventually read that book when I'm done with my current book.
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how to use counting function in c# for counting values
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There is no specialized counter-function. One declares a variable, and increases it's value when required.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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Do you mean the IList<T>.Count()[^] method? If so, instantiate a list of values, add some values to it, and call Count on it.
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If you are going to get help here, you must first learn how to get help for yourself. Look at the questions you have just posted.
Would you be able to answer them if you knew the answer. No is the short reply.
You need to specify what you need. In this case what are you counting, or why do you need to count something. There is no "counting function" in c#.
The other thing is, you need to explain what the problem is. You will get more help if you show effort on your side. Without this (especially with newer members) everyone assumes you just want your work done for you and won't help - we aren't getting paid.
“Education is not the piling on of learning, information, data, facts, skills, or abilities - that's training or instruction - but is rather making visible what is hidden as a seed”
“One of the greatest problems of our time is that many are schooled but few are educated”
Sir Thomas More (1478 – 1535)
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I strongly suggest you work through .NET Book Zero[^], by Charlse Petzold. It will answer most of the questions you have already posted, and more that you haven't.
Use the best guess
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You could implement a counting function in many ways -
1) Run a loop (for-else, while etc)
2) Call a function recursively
3) Use LINQ
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how to print
*******
*****
***
throug nested loof
in c#
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By writing some code. This is a very simple classroom assignment that you should be able to do for yourself. Think about the steps you need to take:
- How many stars do you need to print on each line?
- How can you use a for loop to change that number by a fixed amount?
- What criteria do you need to test in order to decide when the loop is complete?
If necessary, write all the details on paper before you try turning them into code.
Use the best guess
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Are there no lab supervisors to ask. You should ask those, it's a good way of introducing yourself, you'll get more help and understand more.
“Education is not the piling on of learning, information, data, facts, skills, or abilities - that's training or instruction - but is rather making visible what is hidden as a seed”
“One of the greatest problems of our time is that many are schooled but few are educated”
Sir Thomas More (1478 – 1535)
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Try something please, and then post your code and questions here.
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I have this assignment:
Develop a C# console application that implements three arrays; a string array initialized with exactly the following five data items { "Widget 15.50", "Thingy 50.99", "Ratchet25.00", "Clanger115.49", "Fracker75.25" }, a string array to hold the five part names to be parsed from the previously detailed string array, an array of five double value prices to be parsed from the previously mentioned array.
Create a void method that will accept as arguments the two arrays of strings and the array of doubles when called from Main. In the method you will access the five members of the first string array mentioned above and you will parse out the name portion of each string element (first 7 bytes), assigning the string value to the corresponding element in the array of names. In the method you will also parse out the numeric portion of each string and assign it to the corresponding element of the price array. The parsing should be done using the string method SubString.
In Main, after calling the parsing method you will display the elements of both the array of names and the array of prices side-by-side (do not display the array from which you parsed the data items).
The output should look something like this:
Widget $15.50
Thingy $50.99
Ratchet $25.00
Clanger $115.49
Fracker $75.25
Press any key to continue . . .
This is what I have so far and I have an error and I don't know what is wrong:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string[] combo = { "Widget 15.50", "Thingy 50.99", "Ratchet25.00", "Clanger115.49", "Fracker75.25" };
string name = Convert.ToChar(combo[].Substring(0, 7));
double price = Convert.ToInt32(combo[].Substring(7, 12));;
parse(ref combo, ref name, ref price);
}
static void parse(ref string[] combo, ref string name, ref double price)
{
for (int x = 0; x < combo.Length; x++)
{
Console.Write(name + price + "\n");
}
}
}
}
It gives me a syntax error for lines for 14 and 15.
modified 19-May-13 15:23pm.
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Please don't repost the same question; edit your original.
Use the best guess
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It isn't the same question.
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It's exactly the same question, go and read it.
Use the best guess
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They are two different assignment using some of the same information.
My first post ask for using two parallel arrays.
The second post/assignment is using three arrays.
Two different posts for different assignment. The second post piggy backs off of the first post.
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Because
combo[].Substring(0, 7)
a string array does not have a Substring method. You have to supply an index to the array to access an element in the array.
Then the next error is because you cannot convert a char to a string,
string name = Convert.ToChar( . SubString would already be returning a string so why would you try and convert the string to a char anyway?
The next error after that is because you are trying a access a part of the string that does not exist. The parameters for Substring are the starting index and the length,
Substring(7, 12) , starting at index 7 and counting for 12 characters is greater than the length of your string.
Learn to use the debugger, it will serve you well.
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Thanks for the help. I understand those are my errors, but I'm not sure how to fix it. I'm looking in my book and still don't understand it.
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Member 10063234 wrote: still don't understand it
How would I know what it is that you do not understand?
Do you not understand what an array is? Do you not understand how to access an element in an array? For your example, combo is string array yes? To access your first element in the array you need to supply the index of the element that you want to access i.e. combo[0] would let you access the first string of the array. To access the second element, you would need to access index 1, combo[1]. Unless your textbook is the worst book programming book in the universe, this information is in there. When you wrote combo[], you are referring to the entire array and a string array does not have a Substring method, hence your error. An individual string has a Substring method.
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In addition to the errors ThePhantomUpvoted has mentioned, you also need to look at what you are doing with the data, when you have corrected the problem he describes. Why are you converting data to character? What you are writing here:
string name = Convert.ToChar(combo[].Substring(0, 7));
Is the equivalent of
string name = Convert.ToChar("Widget ");
Which is silly: a string is made up of a number of characters (think of it as an array of characters), so you take a string, convert it to a character - which is a silly idea all on it's own - and then try to store the character into a string again!
Take a deep breath, step away from the keyboard and think about what you are trying to do. Then ignore you code for a moment, and use a piece of paper and a pencil to work out exactly how you would do this yourself. When you have that, you should be ready to look at your instructions and work out what to do.
They are quite explicit:
Create a void method that will accept as arguments the two arrays of strings and the array of doubles when called from Main. Does your parse method do exactly that?
The universe is composed of electrons, neutrons, protons and......morons. (ThePhantomUpvoter)
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if all you need to do is print to the screen:
Member 10063234 wrote: Widget $15.50
Thingy $50.99
Ratchet $25.00
Clanger $115.49
Fracker $75.25
I can see this being done with two arrays… One string array and one int array.
I'm also trying to learn C#, most of the people here usually pretty good about helping you understand and learn what things do in this programming language.
They won't rewrite your code or do your homework for you… I on the other hand, would like to take a shot at writing this… It will give me an excuse to practice writing code myself…
As long as you're just looking for something for that simple output, I will post my code…
If you're supposed to be writing it in a certain way, then I won't post.
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