How to solve a usual problem in allocating the size of array

Joe Wilson

11y1.4k

I mean I want to ask user to enter the size of arrays when he/she uses my program instead of me, and when I use cin to get the size and put it as array size in brackets this error appear: the array size must have constant value and when I change the cin parameter as const int nothing happen, please guide me to solve this problem, Thank you.

6 Replies

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Priyaranjan K S11y ago
Hi Joe,

You can try the below code to dynamically modify the array length during run time :
int[] myArray=new int[5]{1,2,3,4,5};

// Accept new array size from user
int newArraySize = 10;
for (int i = 0; i < newArraySize; i++)
{
Array.Resize(ref myArray,newArraySize);
myArray[myArray.Length - 1] = i;
}
Console.WriteLine(myArray.Length);
Output : 10

One important thing to note here is that the Array.Resize wont actually resize the array, it will actually create a new array with the specified size and copies all the elements from the old array to the newly created array and then replaces the old array with the new array.

Thanks,
Priyan

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Atul Rawat11y ago
use C# param arrays
Joe Wilson11y ago
I didn't exactly understand your answer, please explain more, I want end user to enter the size of arrays the program get run.
Joe Wilson11y ago
I exactly want to ask end user to enter the size of array then the program get run,so COULD YOU EXPLAIN THE SOLUTION PLEASE?
Rajeev Ranjan11y ago
So you are trying to assign the size of array at run time??
if yes then assign any value before the run your programe and use a simple logic
to assign user entered value ( something like swapping) that make your code easier and your problem gets resolved.
Preeti Agrawalla11y ago
Hello dear,

This problem might occur, because an user is entering a string value and we can't use string value as an array size. so it will be better to use try catch block, or to check whether entered value is integer or not and provide a message to end user that "please enter numbers".