occurrence.md

---
layout: plugin
title: Occurrence analysis
short: Occurrence
description: Allows the user to reach the statements where a given variable is used. Also provided as a simple example for new plug-in development.
key: browsing
distrib_mode: main
---

## Overview

The **Occurrence analysis** plug-in shows the uses of a variable in a C program.
This analysis highlights the left-values that may access the selected variable.
As shown by the example, the analysis takes aliases into account.

It is available through a contextual menu at each variable in the Frama-C
graphical user interface. Invoking this analysis on a variable displays
the occurrences of this variable in the program:

![Screenshot of Occurrence in the GUI](/assets/img/plugins/occurrence-img.png)


## Usage

The plug-in can be used both with the graphical user interface and in batch mode.
In batch mode, the command is:

    frama-c -occurrence file1.c file2.c

This prints all occurrences of each variable to the standard output.

## Dependencies

This plug-in depends on results of the [Eva](eva.html) plug-in.