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🔧 Mastering Uniface's delitem Statement: Your Guide to List Management

#uniface #database #programming #lists

Hey developers! 👋 Today we're diving deep into one of Uniface's essential list manipulation commands - the delitem statement. Whether you're working with indexed or associative lists, this powerful command will help you manage your data structures efficiently.

📝 Note: This article was created with the assistance of AI and is based on the official Uniface 10.4 documentation.

🎯 What is delitem?

The delitem statement in Uniface 10.4 is your go-to tool for removing items from lists. It's versatile, supporting both indexed and associative lists, and can be used across all component types.

📚 Basic Syntax

There are two main ways to use delitem:

delitem List, N                    // For indexed lists
delitem/id{/case} List, Index      // For associative lists
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🔍 Qualifiers Explained

Qualifier Description
/id Delete item with specific value from associative list
/case Enable case-sensitive matching (use with /id)

📊 Parameters & Return Values

Parameters:

  • List (String): The Uniface list to modify
  • N (Number): Item position in indexed list (1-based)
  • Index (String): Value to find in associative list

Return Values ($status):

  • 0: No item was deleted
  • >0: Item number of the deleted item

💡 Practical Examples

🔢 Working with Indexed Lists 

// Delete the 3rd item from an indexed list
$valrep(DBMSFLD) = "mss;ora;syb;db2"
; ValRep is "mss;ora;syb;db2"
delitem $valrep(DBMSFLD), 3
; ValRep is now "mss;ora;db2"

// Delete the last item using -1
delitem $valrep(DBMSFLD), -1
; Removes the last item from the list
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🏷️ Working with Associative Lists 

// Case-insensitive deletion (default)
$valrep(DATEFLD) = "mon=monday;tue=tuesday;wed=wednesday"
delitem/id $valrep(DATEFLD), "TUE"
; ValRep is now "mon=monday;wed=wednesday"

// Case-sensitive deletion
delitem/id/case $list$, "ab"
; Only deletes items with exact case match
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🔄 Treating Indexed Lists as Associative 

// Same list, different approach
$valrep(DBMSFLD) = "mss;ora;syb;db2"
delitem/id $valrep(DBMSFLD), "syb"
; ValRep is now "mss;ora;db2"
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🚀 Pro Tips

  • 🧹 Clear entire list: Use $1 = "" instead of deleting items one by one
  • ⚡ Performance: For large lists, consider the trade-offs between indexed and associative approaches
  • 🔍 Case sensitivity: Remember that /id is case-insensitive by default - use /case when needed
  • 📝 Item numbering: Uniface uses 1-based indexing, not 0-based

🎯 When to Use delitem

The delitem statement is perfect for:

  • 🔧 Dynamic list management in user interfaces
  • 📋 Removing selected items from dropdown lists
  • 🗂️ Cleaning up data structures during processing
  • ⚙️ Implementing custom list manipulation logic

🎉 Wrapping Up

The delitem statement is a fundamental tool in the Uniface developer's toolkit. Its flexibility with both indexed and associative lists makes it invaluable for dynamic data management. Remember to check the $status return value to ensure your deletions were successful!

Happy coding! 🚀💻

Want to learn more about Uniface? Check out the official documentation and keep exploring this powerful development platform!

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