Migrating Delphi 7 Applications

Delphi 7 migration should begin from a reproducible Delphi 7 build, then introduce compiler, component and platform changes in measurable stages.

Inventory Delphi 7 assumptions

  1. Map third-party VCL components, runtime packages and source availability.
  2. Locate BDE or other database layers, client libraries and SQL behavior.
  3. Review Windows API declarations, pointer/integer casts and external DLL interfaces.
  4. Find code that assumes ANSI strings, byte-based character indexing or specific code pages.
  5. Preserve reports, printers, devices, automation and installer behavior as test cases.

The ANSI-to-Unicode transition can alter buffer sizes, file formats, API calls and external protocols. Adding casts until compilation succeeds can hide data corruption.

Stage the migration

BaselineRebuild and test unchanged behavior in Delphi 7.
ComponentsUpgrade or replace packages with explicit behavior comparisons.
CompilerResolve language, Unicode and API differences with targeted tests.
Data/platformMigrate database or deployment separately when possible.

Use representative data and golden outputs, and retain rollback to the operational version through each release.

See build recovery, Delphi modernization, BDE migration and the Delphi pillar.

Describe your legacy system or problem

Share what still works, what failed, and what must be preserved.

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