OP_EQUAL

INFO

Opcode number: 135
Byte representation: 0x87
Short description: Compare the top two items on the stack and push 1 if they are equal, 0 otherwise.

OP_EQUAL is used to compare the top two items on the stack. If they are equal, it pushes 1 (true) onto the stack; if they are not equal, it pushes 0 (false). Both items being compared are removed from the stack.

Operation

1. Compare the top two items on the stack.
2. If the items are equal, push 1 (true) onto the stack.
3. If the items are not equal, push 0 (false) onto the stack.

Notes

• OP_EQUAL is commonly used in scripts that require equality checks, such as verifying if two hash values or public keys match.
• Both items being compared are consumed (removed) from the stack.
• If there are fewer than two items on the stack when OP_EQUAL is executed, the script will fail.

Examples

Example 1

Comparing two equal items:

# ASM script
OP_1 OP_1 OP_EQUAL

# Raw script
515187

# Stack (before OP_EQUAL)
1
1

# Stack (after OP_EQUAL)
1  # (true, since the two items are equal)

Example 2

Comparing two unequal items:

# ASM script
OP_1 OP_2 OP_EQUAL

# Raw script
515287

# Stack (before OP_EQUAL)
2
1

# Stack (after OP_EQUAL)
0  # (false, since the two items are not equal)