Opcode Explained

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OP_2SWAP ​

INFO

Opcode number: 114
Byte representation: 0x72
Short description: Swap the top two pairs of stack items.

OP_2SWAP is used to swap the top two pairs of items on the stack. The first and second stack items are swapped with the third and fourth items.

Operation ​

  1. Swap the top two items with the third and fourth items on the stack, preserving the order of each pair.

Notes ​

  • This opcode works with pairs of stack items. If there are fewer than four items on the stack when OP_2SWAP is executed, the script will fail.
  • OP_SWAP is a related opcode for swapping just the top two items.

Examples ​

Example 1 ​

Swapping the top two pairs with six total items:

shell
# ASM script
OP_1 OP_2 OP_3 OP_4 OP_5 OP_6 OP_2SWAP

# Raw script
51525354555672

# Stack (before OP_2SWAP)
6  # top
5
4
3
2
1

# Stack (after OP_2SWAP)
4
3
6
5
2
1