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The Printf Module in KDB-X

This page provides an overview of the Printf module in KDB-X.

The Printf module provides a way to format output strings, replicating a subset of the C99 printf standard. It enables you to produce formatted text output using a syntax similar to C’s printf, simplifying the creation of readable and structured text within KDB-X environments.

This module is implemented under the KDB-X module framework and can be loaded into any namespace. While examples in the reference documentation use the root namespace [printf]:use\kx.printf`, you can freely load it under a custom alias within your projects.

At its core, the printf module translates q types into formatted text according to format specifiers embedded within a template string. These specifiers determine how each argument is displayed—whether as an integer, float, hexadecimal value, string, or a q-specific type.

Supported syntax

The general syntax follows:

%[flags][width][.precision]conversion

Notably, the [argument$] and [length modifier] fields from the C specification are excluded due to type system differences.

Use cases

The printf module is most useful for:

  • Readable console output – Producing structured diagnostic or progress messages.
  • Logging frameworks – Integrating formatted output into logging modules.
  • Report generation – Creating human-readable text outputs for analysis results.
  • Interoperability – Providing a C-style formatting approach for developers familiar with mixed language environments.

Integration in KDB-X

Within the KDB-X module framework, printf functions as a utility module, often used as a dependency by other KX modules. It can be referenced via:

([printf]):use`kx.printf

By installing it into the default $HOME/.kx/mod/kx directory, other modules can cross-reference it.

Further information

Refer to the Printf GitHub documentation for: