Opcode Explained

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OP_DEPTH ​

INFO

Opcode number: 116
Byte representation: 0x74
Short description: Push the number of items currently on the stack onto the stack.

OP_DEPTH is used to determine the number of items on the stack and push that count onto the stack as a new item.

Operation ​

  1. Count the number of items currently on the stack.
  2. Push that count (as a number) onto the stack.

Notes ​

  • This opcode is useful when you need to know the size of the stack, for example, before performing operations that require a certain number of stack items.
  • The value pushed by OP_DEPTH does not affect the other items on the stack.

Examples ​

Example 1 ​

Pushing the stack size when there are three items:

shell
# ASM script
OP_1 OP_2 OP_3 OP_DEPTH

# Raw script
51525374

# Stack (before OP_DEPTH)
3
2
1

# Stack (after OP_DEPTH)
3  # depth count
3
2
1

Example 2 ​

Pushing the stack size when there are no items:

shell
# ASM script
OP_DEPTH

# Raw script
74

# Stack (before OP_DEPTH)
(empty stack)

# Stack (after OP_DEPTH)
0  # depth count

Example 3 ​

shell
# ASM script
OP_0 OP_0 OP_0 OP_DEPTH

# Raw script
00000074

# Stack (before OP_DEPTH)
(empty byte array)
(empty byte array)
(empty byte array)

# Stack (after OP_DEPTH)
3  # depth count
(empty byte array)
(empty byte array)
(empty byte array)