How do you use the Array.GetLength function in C#?
What is the difference between the Length property and the GetLength function?
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5 Answers
GetLength takes an integer that specifies the dimension of the array that you're querying and returns its length. Length property returns the total number of items in an array:
int[,,] a = new int[10,11,12];
Console.WriteLine(a.Length); // 1320
Console.WriteLine(a.GetLength(0)); // 10
Console.WriteLine(a.GetLength(1)); // 11
Console.WriteLine(a.GetLength(2)); // 12
5 Comments
Dirk Vollmar
And on one-dimensional arrays
Length will return the same value as GetLength(0).
Mike Pateras
Why is a.GetLength(2) 11 and not 12?
Mehrdad Afshari
@Mike: Cause 1 and 2 are a single key away.
Neo42
Why is a.Length 1320? Why are the a.GetLength values, simply their values? This doesn't make any sense.
Mehrdad Afshari
@Neo42 1320=10x11x12
For 1-dimensional arrays Length and GetLength(0) are exactly the same.
For arrays of higher rank Length is the product of all GetLength(0..Rank-1) values, in other words it is always the total number of fields.
3 Comments
Novice Developer
int[] testArray = {1, 2, 3 , 4} is testArray.GetLength(1) correct?
Anon.
No. Should be
testArray.GetLength(0).
Henk Holterman
divo, "jagged arrays" are arrays of arrays, at each level rank==1. They are not multi-dimensional in the same way.
The .Length property returns the number of elements in an array, whether it be one dimensional or multidimensional. That is a 2x6 array will have length of 12.
The .GetLength(0) method returns number of elements in the row direction in a multidimensional array. For a 2x6 array that is 2.
The .GetLength(1) method returns number of elements in the column direction in a multidimensional array. For a 2x6 array that is 6.
These do not return an actual element value, as stated by the chosen answer above.
Comments
GetLength returns the length of a specified dimension of a mulit-dimensional array.
Length returns the sum of the total number of elements in all the dimensions.
- For a single-dimensional array, Length == GetLength(0)
- For a two-dimensional array, Length == GetLength(0) * GetLength(1)
etc.
2 Comments
Mehrdad Afshari
Not quite true: Two dimensional arrays: Length = GetLength(0) * GetLength(1)
Jason Williams
That's a clever typo! How did I manage to transpose + and * ?! (fixed)
In mathematical term, we call as m rows and n columns, so the results is product of m*n for a two dimensional array. In this case GetLength(0) = m rows and GetLength(1)= n columns. For e.g see below example
string[,] stocks ={{"RELIND","Reliance Industries","1006.30"},{"TATMOB","Tata Mobiles","504.10"},{"ALST","Allstate","800.00"}, {"GE","GE Motors","810.00"}
};
The stocks arrays return GetLength(0)= 4 and GetLength(1)=3 and length =12
1 Comment
user8107351
GetLength(0)= 3 and GetLength(1)=2. It returns the index(which starts from zero) of the element, not the actual element count. I was confused by this for a minute. so I had to clarify.