# Combining Stack Operations

Real-world scripts rarely use stack operations in isolation. The power comes from **combining them efficiently** to achieve **complex data manipulation** with **minimal opcodes**.

### Pattern 1: Duplicate-Check-Drop

```
// Check if a value matches expected without consuming it x OP_DUP <expected> OP_EQUAL OP_VERIFY // Stack still has: x
```

### Pattern 2: Reach Deep and Compare

```
// Compare item at depth 3 with top item x1 x2 x3 x4 OP_3 OP_PICK // Copy x1 to top OP_OVER // Copy x4 beneath it OP_EQUAL // Compare // Original stack unchanged except for comparison result
```

### Pattern 3: Conditional Storage

```
x OP_IFDUP OP_IF OP_TOALTSTACK // Process with x stored ... OP_FROMALTSTACK OP_ELSE // Process without storage ... OP_ENDIF
```


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