# String Manipulation Fully Restored

Chronicle restored the complete set of string manipulation opcodes:

| Opcode         | Input     | Output    | Restored Function                           |
| -------------- | --------- | --------- | ------------------------------------------- |
| **OP\_CAT**    | x1 x2     | x1\|x2    | Concatenates two byte sequences             |
| **OP\_SUBSTR** | x pos len | substring | Extracts substring from position for length |
| **OP\_LEFT**   | x n       | left\_n   | Returns leftmost n bytes                    |
| **OP\_RIGHT**  | x n       | right\_n  | Returns rightmost n bytes                   |

**OP\_CAT: Concatenation**

**OP\_CAT** joins two byte sequences into one: 

```
0x1234 0x5678 OP_CAT
# Result: 0x12345678
```

**Why OP\_CAT matters:**

You can directly concatenate data for building structures, combining signature elements, creating messages, and constructing Merkle tree proofs.

#### OP\_SUBSTR: Substring Extraction

**OP\_SUBSTR** extracts a portion of a byte sequence starting at a specific position:

```
0x12345678 OP_1 OP_2 OP_SUBSTR
# Extracts 2 bytes starting at position 1: 0x3456
```

**Common use cases:**

* Parsing structured data formats
* Extracting specific fields from complex messages
* Protocol implementations requiring precise data extraction

#### OP\_LEFT and OP\_RIGHT: Boundary Extraction

**OP\_LEFT** returns the leftmost bytes:

```
0x12345678 OP_2 OP_LEFT
# Returns first 2 bytes: 0x1234
```

**OP\_RIGHT** returns the rightmost bytes:

```
0x12345678 OP_2 OP_RIGHT
# Returns last 2 bytes: 0x5678
```

These opcodes simplify extracting data from the beginning or end of byte sequences without calculating positions.


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