gets tcl

Overview

Read a line from a file

Syntax

gets fileId ?varName?

Description

This command reads the next line from the file given by fileId and discards the terminating newline character. If varName is specified then the line is placed in the variable by that name and the return value is a count of the number of characters read (not including the newline). If the end of the file is reached before reading any characters then -1 is returned and varName is set to an empty string. If varName is not specified then the return value will be the line (minus the newline character) or an empty string if the end of the file is reached before reading any characters. An empty string will also be returned if a line contains no characters except the newline, so eof may have to be used to determine what really happened. If the last character in the file is not a newline character then gets behaves as if there were an additional newline character at the end of the file. fileId must be stdin or the return value from a previous call to open; it must refer to a file that was opened for reading.

Any existing end-of-file or error condition on the file is cleared at the beginning of the gets command.

Keywords

file, line, read

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