Client APIs
API Reference Overview
> **Deprecated.  ** This method has been deprecated. Prefer using `duckdb_result_get_chunk` instead.  
Returns the nullmask of a specific column of a result in columnar format. The nullmask indicates for every row
whether or not the corresponding row is `NULL`. If a row is `NULL`, the values present in the array provided
by `duckdb_column_data` are undefined.  
```c
int32_t *data = (int32_t *) duckdb_column_data(&result, 0);
bool *nullmask = duckdb_nullmask_data(&result, 0);
if (nullmask[row]) {
printf("Data for row %d: NULL\n", row);
} else {
printf("Data for row %d: %d\n", row, data[row]);
}
```  
###### Syntax {#docs:api:c:api::syntax}  
```c
bool *duckdb_nullmask_data(
duckdb_result *result,
idx_t col
);
```  
###### Parameters {#docs:api:c:api::parameters}  
* `result`: The result object to fetch the nullmask from.
* `col`: The column index.  
###### Return Value {#docs:api:c:api::return-value}  
The nullmask of the specified column.  
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