OP_SIZE

INFO

Opcode number: 130
Byte representation: 0x82
Short Description: Push the length of the top stack item in bytes onto the stack

The OP_SIZE opcode pushes the length of the top stack item in bytes onto the stack.

NOTES

• The stack item that was previously the top stack item is unaffected and simply becomes the second item on the stack following the output from OP_SIZE
• If the stack is empty the script fails.

Examples

Example 1

Measuring the length of 0 as an empty byte array results in a length of 0:

# ASM script
OP_0 OP_SIZE

# Raw script
0082

# Final stack
0
0

Example 2

Any opcode that returns true pushes to the stack a 1 which is a single byte:

# ASM script
OP_1 OP_2 OP_ADD OP_3 OP_EQUAL OP_SIZE

# Raw script
515293538782

# Final stack
1
1

Example 3

OP_SIZE measures the length in bytes and since OP_PUSHBYTES_3 always pushes 3 bytes the length will be 3:

# ASM script
OP_PUSHBYTES_3 a4b5c6 OP_SIZE

# Raw script
03a4b5c682

# Final stack
3
a4b5c6