# 18.2.348. MPI_T_category_get_info

MPI_T_category_get_info — Query information from a category

## 18.2.348.1. SYNTAX

### 18.2.348.1.1. 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)

## 18.2.348.2. INPUT PARAMETERS

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

## 18.2.348.3. 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.

## 18.2.348.4. 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.

## 18.2.348.5. 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.

## 18.2.348.6. 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.

## 18.2.348.7. 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