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CountOccurrences()

Count pattern occurrences without storing positions (memory efficient).

📋 Description

CountOccurrences() counts how many times a byte pattern appears in the file without storing positions, making it much more memory-efficient than FindAll().Count() for large files.

📝 Signature

public int CountOccurrences(byte[] pattern, long startPosition = 0)

Since: V2.0

⚙️ Parameters

Parameter Type Description Default
pattern byte[] Byte pattern to count -
startPosition long Position to start from 0

🔄 Returns

Type Description
int Number of occurrences found

🎯 Examples

Example 1: Count Pattern

// Count how many times 0xFF appears
var pattern = new byte[] { 0xFF };
int count = hexEditor.CountOccurrences(pattern);
Console.WriteLine($"Found {count} occurrences of 0xFF");

Example 2: Count Multi-Byte Pattern

// Count null-terminated strings
var nullTerm = new byte[] { 0x00 };
int stringCount = hexEditor.CountOccurrences(nullTerm);

// Count specific signature
var signature = new byte[] { 0xDE, 0xAD, 0xBE, 0xEF };
int signatureCount = hexEditor.CountOccurrences(signature);

Example 3: Count From Position

// Count occurrences after position 0x1000
var pattern = new byte[] { 0xAA, 0xBB };
int count = hexEditor.CountOccurrences(pattern, startPosition: 0x1000);

⚡ Performance vs FindAll()

Memory Usage Comparison

File Size Matches FindAll().Count() Memory CountOccurrences() Memory
10 MB 1,000 ~8 KB ~0 KB
100 MB 10,000 ~80 KB ~0 KB
1 GB 100,000 ~800 KB ~0 KB

When to Use What

Scenario Use CountOccurrences() Use FindAll()
Only need count ✅ Yes ❌ No
Need positions ❌ No ✅ Yes
Large file ✅ Yes ⚠️ May use lots of memory
Many matches ✅ Yes ⚠️ High memory usage

💡 Use Cases

1. Statistics

// Analyze byte frequency
int nullBytes = hexEditor.CountOccurrences(new byte[] { 0x00 });
int ffBytes = hexEditor.CountOccurrences(new byte[] { 0xFF });
Console.WriteLine($"File contains {nullBytes} null bytes and {ffBytes} FF bytes");

2. Validation

// Check if pattern exists before processing
var pattern = new byte[] { 0x4D, 0x5A }; // MZ header
int count = hexEditor.CountOccurrences(pattern);

if (count == 0)
{
    Console.WriteLine("No PE executables found");
}
else
{
    Console.WriteLine($"Found {count} potential PE executables");
}

3. Progress Reporting

// Count total before processing
var pattern = new byte[] { 0xAA, 0xBB };
int total = hexEditor.CountOccurrences(pattern);

// Now process each (using FindAll for positions)
int processed = 0;
foreach (var pos in hexEditor.FindAll(pattern))
{
    // Process...
    processed++;
    Console.WriteLine($"Progress: {processed}/{total}");
}

🔗 See Also

Last Updated: 2026-02-19