Explain the difference between StreamReader and File.ReadAllLines().

Question

Anubhav Kumar · Answer

The difference between StreamReader and File.ReadAllLines() in C# lies mainly in
how they read the file and when you would use each.
File.ReadAllLines(string path)
Reads all lines of a text file at once.Returns a string[] (array of strings).File is opened, read, and closed automatically.Not suitable for very large files (can use a lot of memory).
Example:
string[] lines = File.ReadAllLines("example.txt");
foreach (string line in lines)
{
    Console.WriteLine(line);
}
StreamReader
Reads a file line-by-line or character-by-character.Gives more control over reading (e.g., read a specific number of lines, skip lines, read partial content).Better for large files or streamed reading.You manually control the reading process and resource disposal (usually with
using).
Example:
using (StreamReader reader = new StreamReader("example.txt"))
{
    string line;
    while ((line = reader.ReadLine()) != null)
    {
        Console.WriteLine(line);
    }
}
Summary of Differences
Feature
File.ReadAllLines()
StreamReader
Reads entire file
Yes
No (line-by-line or custom reading)
Returns
string[]
Each line via ReadLine()
Memory usage
High (if file is large)
Low (reads as needed)
Suitable for large files
No
Yes
Custom read logic
No
Yes
Ease of use
Simple
Requires more control
When to Use Which?
Use File.ReadAllLines() for small to medium files when you want all lines immediately.Use StreamReader for large files or when you need
streamed/customized reading logic.

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Explain the difference between StreamReader and File.ReadAllLines().

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1 Answers

`File.ReadAllLines(string path)`

`StreamReader`

Summary of Differences

When to Use Which?

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Feature	`File.ReadAllLines()`	`StreamReader`
Reads entire file	Yes	No (line-by-line or custom reading)
Returns	`string[]`	Each line via `ReadLine()`
Memory usage	High (if file is large)	Low (reads as needed)
Suitable for large files	No	Yes
Custom read logic	No	Yes
Ease of use	Simple	Requires more control