Using multiple inputs
Tools can accept a single input or many inputs, depending on the operation. Tools that convert or overlay data can accept multiple datasets as input because of the nature of the operation. In a program, inputs are passed to these tools as a multivalue string, which uses a semicolon to separate each input in the string. A multivalue string is easy to construct in a program using the string manipulation functions built into the language.
In the following code example, a multivalue string is created with VB.NET and CSharp (C#) concatenation capabilities and used with the Union tool:
[C#] public void ExampleGPUsingMultipleInputs()
{
// Initialize the geoprocessor.
Geoprocessor GP=new Geoprocessor();
// Initialize the Union tool.
Union uniontool=new Union();
// List all feature classes in the workspace.
GP.SetEnvironmentValue("workspace", @"C:\studyarea");
IGpEnumList fcColl=GP.ListFeatureClasses("*", "", "");
// Create a StringBuilder object and add the feature classes as a semicolon-delimited list.
StringBuilder sb=new StringBuilder();
string inputfeatures=fcColl.Next();
while (inputfeatures != "")
{
sb.AppendFormat("{0};", inputfeatures);
inputfeatures=fcColl.Next();
}
// Execute the Union tool with multiple inputs creating landuse.shp.
uniontool.in_features=sb.ToString();
uniontool.out_feature_class="landuse.shp";
GP.Execute(uniontool, null);
}
[VB.NET] Public Sub ExampleGPUsingMultipleInputs()
' Initialize the geoprocessor.
Dim GP As Geoprocessor=New Geoprocessor()
' Initialize the Union tool.
Dim uniontool As Union=New Union()
' List all feature classes in the workspace.
GP.SetEnvironmentValue("workspace", "C:\studyarea")
Dim fcColl As ESRI.ArcGIS.Geoprocessing.IGpEnumList=GP.ListFeatureClasses("*", "", "")
' Create a StringBuilder object and add the feature classes as a semicolon-delimited list.
Dim sb As StringBuilder=New StringBuilder()
Dim inputfeatures As String=fcColl.Next()
Do While inputfeatures <> ""
sb.AppendFormat("{0};", inputfeatures)
inputfeatures=fcColl.Next()
Loop
' Execute the Union tool with multiple inputs creating landuse.shp.
uniontool.in_features=sb.ToString()
uniontool.out_feature_class="landuse.shp"
GP.Execute(uniontool, Nothing)
End Sub
See Also:
How Union worksTo use the code in this topic, reference the following assemblies in your Visual Studio project. In the code files, you will need using (C#) or Imports (VB .NET) directives for the corresponding namespaces (given in parenthesis below if different from the assembly name):