---
name: "MPI_T_category_get_info"
section: "3"
platform: "linux"
package: "openmpi"
version: "5.0.11-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/MPI_T_category_get_info"
---

# MPI\_T\_category\_get\_info(3)

*MPI\_T\_category\_get\_info* — Query information from a category

## SYNTAX

### C Syntax

```
#include <mpi.h>
int MPI_T_category_get_info(int cat_index, char *name, int *name_len,
char *desc, int *desc_len, int *num_cvars, int *num_pvars,
int *num_categories)
```

## INPUT PARAMETERS

- •

  **cat\_index**: Index of the category to be queried.

## INPUT/OUTPUT PARAMETERS

- •

  **name\_len**: Length of the string and/or buffer for name.

- •

  **desc\_len**: Length of the string and/or buffer for desc.

## OUTPUT PARAMETERS

- •

  **name**: Buffer to return the string containing the name of the category.

- •

  **desc**: Buffer to return the string containing the description of the category.

- •

  **num\_cvars**: Number of control variables in the category.

- •

  **num\_pvars**: Number of performance variables in the category.

- •

  **num\_categories**: Number of categories contained in the category.

## DESCRIPTION

*MPI\_T\_category\_get\_info* can be used to query information from a category. The function returns the number of control variables, performance variables, and sub-categories in the queried category in the arguments *num\_cvars*, *num\_pvars*, and *num\_categories*, respectively.

## NOTES

This MPI tool interface function returns two strings. This function takes two argument for each string: a buffer to store the string, and a length which must initially specify the size of the buffer. If the length passed is n then this function will copy at most n - 1 characters of the string into the corresponding buffer and set the length to the number of characters copied - 1. If the length argument is NULL or the value specified in the length is 0 the corresponding string buffer is ignored and the string is not returned.

## ERRORS

*MPI\_T\_category\_get\_info* will fail if:

- •

  **MPI\_T\_ERR\_NOT\_INITIALIZED**: The MPI Tools interface not initialized

- •

  **MPI\_T\_ERR\_INVALID\_INDEX**: The category index is invalid

## COPYRIGHT

2003-2026, The Open MPI Community