Whatever message this page gives is out now! Go check it out!
FileReadLines
Last update:
May 18, 2026
Reads a specified number of lines from a file starting at a given position, with support for forward and backward reading.
Description
The function enables efficient multi-line reading from files without loading the entire file into memory.
The function supports reading forward, backward (using negative counts), and reading to end-of-file when the count is omitted.
Syntax
FileReadLines(Object file, long startLine [, long count])| Parameter | Type | Description |
|---|---|---|
| file | String or FileStreamWrapper (required) | File path or FileOpen() object. |
| startLine | long (required) | 0-based line number to start reading. |
| count | long (optional) | Number of lines to read. Positive reads forward, negative reads backward. Omit to read to EOF. |
Returns
Array of Strings: One element per line read.
Usage Notes
- Supports Unix (LF), Windows (CRLF), and mixed line endings.
- Negative count reads lines before the start position.
- File paths auto-open and auto-close.
- FileStreamWrapper enables reusable file handles.
Basic- Read First N Lines
<cfscript>
lines = FileReadLines(expandPath("./sample.txt"), 0, 3);
writeOutput(ArrayLen(lines));
</cfscript>Read All Lines to EOF
<cfscript>
lines = FileReadLines(expandPath("./sample.txt"), 0);
writeOutput(ArrayLen(lines));
</cfscript>Read from Middle
<cfscript>
lines = FileReadLines(expandPath("./sample.txt"), 1, 3);
writeOutput(lines[1]);
</cfscript>Backward Reading
<cfscript>
lines = FileReadLines(expandPath("./sample.txt"), 3, -2);
writeOutput(ArrayLen(lines));
</cfscript>Using FileStreamWrapper
<cfscript>
fs = FileOpen(expandPath("./sample.txt"), "read");
lines = FileReadLines(fs, 1, 2);
FileClose(fs);
</cfscript>Closure Integration
<cfscript>
lines = FileReadLines(expandPath("./fruits.txt"), 0);
upper = lines.map(function(l){ return UCase(l); });
writeOutput(ArrayToList(upper));
</cfscript>Error- Non-Existent File
<cfscript>
try {
FileReadLines("missing.txt",0,5);
} catch(any e){
writeOutput(e.type);
}
</cfscript>Error- Closed Stream
<cfscript>
fs = FileOpen("sample.txt","read");
FileClose(fs);
FileReadLines(fs,0,5);
</cfscript>
We're glad. Tell us how this page helped.
We're sorry. Can you tell us what didn't work for you?
Share additional feedback to help us improve.
0/255
|
