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Program to find the product of odd numbers from 1 to n and the sum of the squares of even numbers according to the number n entered from the keyboard [closed]

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I'm new to the programming world and I'm learning C#. I have an algorithm given to me in expression language and I need to do it with C# .NET Framework console application, but I'm not very good at it. Can you help?
Here's the algorithm I'm talking about;
Start
int toplam, carpım, karetoplam
toplam=0
carpım=1
Read N
6.Cycle I=1, N, 1
if(N%2==1)
toplam=toplam+I
carpım=carpım*I
else
karetoplam=karetoplam+(I*I)
if over
cycle over
Cw toplam
Cw carpım
Cw karetoplam
Done

I only understood the title of your post not the text ;)
Code is untested. Could be optimized to 1 for-loop in 1 method.
Product of oddnumber from 1 to n?
long GetProductsOfOddNumbers(int n) {
var product = 1L;
for (var i = 1; i <= n; i++) {
if (i % 2 == 0) continue;
product *= i;
}
return product;
}
Sum of squares of even numbers from 1 to n?
long GetSumOfSquaresOfEvenNumbers(int n) {
var sum = 0L;
for (var i = 1; i <= n; i++) {
if (i % 2 != 0) continue;
sum += (i * i);
}
return sum ;
}

plusMinus function from Hacker Rank [closed]

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I'm trying to solve a task from HackerRank, but I'm not able to solve it. Any help is appreciated!
public static void plusMinus(List<int> arr)
{
float noOfPositive = 0;
float noOfNegative = 0;
float noOfZero = 0;
float length = arr.Count;
for(var i = 0; i < arr.Count; i++){
if(i > 0){
noOfPositive += 1;
}else if(i == 0){
noOfZero += 1;
}else{
noOfNegative += 1;
}
}
Console.WriteLine($"{noOfPositive/length}\n{noOfNegative/length}\n{noOfZero/length}");
input:
6
-4 3 -9 0 4 1
My Result:
0.8333333
0
0.1666667
Expected:
0.500000
0.333333
0.166667

You are checking the value of i not arr[i].
So your code should be:
for(var i = 0; i < arr.Count; i++){
if(arr[i] > 0){
noOfPositive += 1;
}else if(arr[i] == 0){
noOfZero += 1;
}else{
noOfNegative += 1;
}
}
And your expected values are wrong, you are putting in 7 items and expecting half of them to be positive so 3.5 items are positive?

Program generates 50 random numbers (between 1 to 10) and tells the amount of values that are smaller than 5 and bigger than 5 (C#) [closed]

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Program generates 50 random numbers (between 1 to 10) and tells the amount of values that are smaller than 5 and bigger than 5 (C#)

Try this:
int n = 50
IList<int> randomNumbers = new List<int>(n);
Random ran = new Random(1);
for (int i = 0; i < n; i++)
{
randomNumbers.Add(ran.Next(1, 10));
}
int lessThan5Count = randomNumbers.Count(c => c < 5);
int greaterThan5Count = randomNumbers.Count(c => c > 5);

You could do it like that:
Random r = new Random();
int n = 50;
int smaller_than_5 = 0;
int bigger_than_5 = 0;
double[] d = new double[n];
for (int i = 0; i < n; i++)
{
d[i] = 1 + r.NextDouble() * 9;
if (d[i] < 5) smaller_than_5++;
else if (d[i] > 5) bigger_than_5++;
}
Hope this helps ...

Adding new value to String array based on condition [closed]

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String Array contains values like {'2','4','8'}
if 8 is present, want to add 999 to it,if string array contains 999 want to add 8 to it.
If both 8 and 999 are present in array no need to add any value to array.

Have a look at the following:
public string[] Add8or999(string[] source)
{
string[] output = source;
if (source.Contains("8") && source.Contains("999"))
{
// what to do here?
}
else if (source.Contains("8"))
{
output = new string[source.Length + 1];
for (int i = 0; i < source.Length; i++)
{
output[i] = source[i];
}
output[source.Length] = "999";
}
else if (source.Contains("999"))
{
output = new string[source.Length + 1];
for (int i = 0; i < source.Length; i++)
{
output[i] = source[i];
}
output[source.Length] = "8";
}
return output;
}
Basic Usage:
string[] s = Add8or999(new string[] {"8", "9", "10"});

Array ints and replace the order of number I write [closed]

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I try Start the console and after i write 5 numbers is do exsepsion what wrong in code
what the console do is after I write 5 number for example 7,4,9,5,1 ---> 1,5,9,4,7
this what I wrote
static void Main(string[] args)
{
int[] numbers = new int[5];
for (int i = 0; i < numbers.Length ; i++)
{
Console.Write("");
numbers[i] = int.Parse(Console.ReadLine());
}
for (int i = 0; i < numbers.Length / 2; i++)
{
int x = numbers[i];
numbers[i] = numbers[numbers.Length - i - 1];
numbers[numbers.Length - i - 1] = x;
}
Console.Read();

You missed two things. First - in order to swap two array items, you need to store item somewhere. Otherwise you just replace one item with other. Second - arrays have indexes from 0 to Length - 1. So you need to subtract 1 from second item index:
for (int i = 0; i < numbers.Length / 2; i++)
{
int x = numbers[i];
numbers[i] = numbers[numbers.Length - i - 1];
numbers[numbers.Length - i - 1] = x;
}