# 17.2.363. MPI_T_pvar_get_num

MPI_T_pvar_get_num — Query the number of performance variables

## 17.2.363.1. SYNTAX

### 17.2.363.1.1. C Syntax

    #include <mpi.h>

    int MPI_T_pvar_get_num(int *num_pvar)

## 17.2.363.2. OUTPUT PARAMETERS

- `num_pvar`: Current number of performance variables.

## 17.2.363.3. DESCRIPTION

MPI_T_pvar_get_num can be used to query the current number of performance variables. The number of performance variables may increase throughout the execution of the process but will never decrease.

## 17.2.363.4. ERRORS

MPI_T_pvar_get_num will fail if:

- `MPI_T_ERR_NOT_INITIALIZED`: The MPI Tools interface not initialized