# 17.2.351. MPI_T_category_get_pvars

MPI_T_category_get_pvars — Query which performance variables are in a category

## 17.2.351.1. SYNTAX

### 17.2.351.1.1. C Syntax

    #include <mpi.h>

    int MPI_T_category_get_pvars(int cat_index, int len, int indices[])

## 17.2.351.2. INPUT PARAMETERS

- `cat_index`: Index of the category to be queried.

- `len`: The length of the indices array.

## 17.2.351.3. OUTPUT PARAMETERS

- `indices`: An integer array of size len, indicating performance variable indices.

## 17.2.351.4. DESCRIPTION

MPI_T_category_get_pvars can be used to query which performance variables are contained in a particular category. A category contains zero or more performance variables.

## 17.2.351.5. ERRORS

MPI_T_category_get_pvars will fail if:

- `MPI_T_ERR_NOT_INITIALIZED`: The MPI Tools interface not initialized

- `MPI_T_ERR_INVALID_INDEX`: The category index is invalid