When I run my code it keeps giving me an error:

File "C:\Users\Joshua Ajogu Alfa\Desktop\merklehashtreebuild1.py", line 36, in inputString = sys.argv[1] IndexError: list index out of range

#!/usr/bin/python
import hashlib,sys
    
class MerkleTreeNode:
    def __init__(self,value):
        self.left = None
        self.right = None
        self.value = value
        self.hashValue = hashlib.sha256(value.encode('utf-8')).hexdigest()
    
def buildTree(leaves,f):
    nodes = []
    for i in leaves:
        nodes.append(MerkleTreeNode(i))

    while len(nodes)!=1:
        temp = []
        for i in range(0,len(nodes),2):
            node1 = nodes[i]
            if i 1 < len(nodes):
                node2 = nodes[i 1]
            else:
                temp.append(nodes[i])
                break
            f.write("Left child : "  node1.value   " | Hash : "   node1.hashValue  " \n")
            f.write("Right child : "  node2.value   " | Hash : "   node2.hashValue  " \n")
            concatenatedHash = node1.hashValue   node2.hashValue
            parent = MerkleTreeNode(concatenatedHash)
            parent.left = node1
            parent.right = node2
            f.write("Parent(concatenation of "  node1.value   " and "   node2.value   ") : "  parent.value   " | Hash : "   parent.hashValue  " \n")
            temp.append(parent)
        nodes = temp 
    return nodes[0]

inputString = sys.argv[1]
leavesString = inputString[1:len(inputString)-1]
leaves = leavesString.split(",")
f = open("merkle.tree", "w")
root = buildTree(leaves,f)
f.close()

CodePudding user response：

You can call the program with arguments like this:

python program.py something another

Also I think adding a except block or checking the length of arguments before is better:

try:
   inputString = sys.argv[1]
except IndexError:
   pass # <- do something if there's no argument

## OR
if len(sys.argv) > 1:
   inputString = sys.argv[1]
else:
   pass # <- do something

CodePudding user response：

you aren't passing the arguments to the file while starting it, do it in this way:

python C:/path/to/your/python/file.pi arg1 arg2 arg3

to avoid any error consider to do:

   try:
       inputString = sys.argv[1]
   except ValueError:
       inputstring = input("please add your input string: ")
       # do anything you want if you dislike this    

Note: remember that you always have a sys.argv list that contains only the filename [main.py]

CodePudding user response：

sys.argv is set by the command you run (i'll treat windows since it's your situation)

maybe trying to run a small program like this one will help

import sys

print(*sys.argv)

the rule of argv is that the first argument (sys.arg[0]) is the name of your program as you writen it in the CLI and the next are strings that contains each arguments you passed so running:

python prog.py 2 arg1 arg2 will set argv at : ["prog.py", "2", "arg1", "arg2"]

normaly a whitespace separate argument but you can use double quote to ignore them.

running: python prog.py 1 "arg1 arg2" will set argv at : ["prog.py", "2", "arg1 arg2"]

in your case it look like you are not giving any argument to your program since argv[1] does not exist.