Array::IndexOf Method (Array, Object, Int32)
Searches for the specified object and returns the index of the first occurrence within the range of elements in the one-dimensional Array that extends from the specified index to the last element.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- array
- Type: System::Array
The one-dimensional Array to search.
- value
- Type: System::Object
The object to locate in array.
- startIndex
- Type: System::Int32
The starting index of the search. 0 (zero) is valid in an empty array.
Return Value
Type: System::Int32The index of the first occurrence of value within the range of elements in array that extends from startIndex to the last element, if found; otherwise, the lower bound of the array minus 1.
| Exception | Condition |
|---|---|
| ArgumentNullException | array is nullptr. |
| ArgumentOutOfRangeException | startIndex is outside the range of valid indexes for array. |
| RankException | array is multidimensional. |
The one-dimensional Array is searched forward starting at startIndex and ending at the last element.
The elements are compared to the specified value using the Object::Equals method. If the element type is a nonintrinsic (user-defined) type, the Equals implementation of that type is used.
Since most arrays will have a lower bound of zero, this method would generally return –1 when value is not found. In the rare case that the lower bound of the array is equal to Int32::MinValue and value is not found, this method returns Int32::MaxValue, which is System.Int32.MinValue - 1.
Passing the Length of the array as the startindex will result in a return value of -1, while values greater than Length will raise an ArgumentOutOfRangeException.
This method is an O(n) operation, where n is the number of elements from startIndex to the end of array.
In the .NET Framework version 2.0, this method uses the Equals and CompareTo methods of the Array to determine whether the Object specified by the value parameter exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the value Object itself.
The following code example shows how to determine the index of the first occurrence of a specified element.
using namespace System; void PrintIndexAndValues( Array^ myArray ); void main() { // Creates and initializes a new Array instance with three elements of the same value. Array^ myArray = Array::CreateInstance( String::typeid, 12 ); myArray->SetValue( "the", 0 ); myArray->SetValue( "quick", 1 ); myArray->SetValue( "brown", 2 ); myArray->SetValue( "fox", 3 ); myArray->SetValue( "jumped", 4 ); myArray->SetValue( "over", 5 ); myArray->SetValue( "the", 6 ); myArray->SetValue( "lazy", 7 ); myArray->SetValue( "dog", 8 ); myArray->SetValue( "in", 9 ); myArray->SetValue( "the", 10 ); myArray->SetValue( "barn", 11 ); // Displays the values of the Array. Console::WriteLine( "The Array instance contains the following values:" ); PrintIndexAndValues( myArray ); // Searches for the first occurrence of the duplicated value. String^ myString = "the"; int myIndex = Array::IndexOf( myArray, myString ); Console::WriteLine( "The first occurrence of \"{0}\" is at index {1}.", myString, myIndex ); // Searches for the first occurrence of the duplicated value in the last section of the Array. myIndex = Array::IndexOf( myArray, myString, 4 ); Console::WriteLine( "The first occurrence of \"{0}\" between index 4 and the end is at index {1}.", myString, myIndex ); // Searches for the first occurrence of the duplicated value in a section of the Array. myIndex = Array::IndexOf( myArray, myString, 6, 5 ); Console::WriteLine( "The first occurrence of \"{0}\" between index 6 and index 10 is at index {1}.", myString, myIndex ); } void PrintIndexAndValues( Array^ myArray ) { for ( int i = myArray->GetLowerBound( 0 ); i <= myArray->GetUpperBound( 0 ); i++ ) Console::WriteLine( "\t[{0}]:\t{1}", i, myArray->GetValue( i ) ); } /* This code produces the following output. The Array instance contains the following values: [0]: the [1]: quick [2]: brown [3]: fox [4]: jumped [5]: over [6]: the [7]: lazy [8]: dog [9]: in [10]: the [11]: barn The first occurrence of "the" is at index 0. The first occurrence of "the" between index 4 and the end is at index 6. The first occurrence of "the" between index 6 and index 10 is at index 6. */
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.