arno/bitcoinbook
1
0
Fork 0
mirror of https://github.com/bitcoinbook/bitcoinbook synced 2024-11-26 01:50:42 +00:00
Code Issues Releases Wiki Activity

Edited ch07.asciidoc with Atlas code editor

Browse Source
This commit is contained in:
judymcconville@roadrunner.com 2017-05-01 12:34:12 -07:00
parent 22f6661ecb
commit e6630726d3
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
ch07.asciidoc
View File

@ -427,7 +427,7 @@ When reading Bitcoin Script, remember that the condition being evaluated comes _
==== Conditional Clauses with VERIFY Opcodes
((("VERIFY opcodes")))((("IF clauses")))Another form of conditional in Bitcoin Script is any opcode that ends in +VERIFY+. The +VERIFY+ suffix means that if the condition evaluated is not +TRUE+, execution of the script terminates immediately and the transaction is deemed invalid.
((("VERIFY opcodes")))((("IF clauses")))((("opcodes", "VERIFY")))Another form of conditional in Bitcoin Script is any opcode that ends in +VERIFY+. The +VERIFY+ suffix means that if the condition evaluated is not +TRUE+, execution of the script terminates immediately and the transaction is deemed invalid.
((("guard clauses")))Unlike an +IF+ clause, which offers alternative execution paths, the +VERIFY+ suffix acts as a _guard clause_, continuing only if a precondition is met.
@ -470,7 +470,7 @@ So, when do we use +VERIFY+ and when do we use +IF+? If all we are trying to do
[TIP]
====
An opcode such as +EQUAL+ will push the result (+TRUE+/+FALSE+) onto the stack, leaving it there for evaluation by subsequent opcodes. In contrast, the opcode +EQUALVERIFY+ suffix does not leave anything on the stack. Opcodes that end in +VERIFY+ do not leave the result on the stack.
((("EQUAL opcodes")))((("opcodes", "EQUAL")))((("EQUALVERIFY opcode")))((("opcodes", "EQUALVERIFY")))An opcode such as +EQUAL+ will push the result (+TRUE+/+FALSE+) onto the stack, leaving it there for evaluation by subsequent opcodes. In contrast, the opcode +EQUALVERIFY+ suffix does not leave anything on the stack. Opcodes that end in +VERIFY+ do not leave the result on the stack.
====
==== Using Flow Control in Scripts