Reads a row from an input stream. Returns one of the following codes:
| Return Code | Description |
|---|---|
| 0 | The operation was successful. |
| -1 | The end of stream was reached. |
| -2 | The table operator aborted. |
| -3 | The input parameter has an invalid type. |
| -4 | The input parameter has an invalid value. |
| -5 | This function was called from the contract function. |
Syntax
tdr.Read( handle )
Syntax Elements
- handle
- Parameter type: raw vector
The handle of the input stream returned by the tdr.Open function.
Usage Notes
Before you call this function, you must call the tdr.Open function to open the input stream. Then pass the handle returned from tdr.Open as an argument to this function.
This function is valid only if called from the table operator.
Example: Reading Rows From the Input Stream
This example opens an input stream and counts the number of rows successfully read from the input stream.
# Open the input stream.
library(tdr); stream <- 0; options <- 0; direction <- "R"; inHandle <- tdr.Open(direction, stream, options);
# Read rows from the input stream.
nrrows <- 0;
while (tdr.Read(inHandle) == 0) {
nrrows <- nrrows+1;
}