Python: list index out of range error

Question

I get this error on the line: if line[0].startswith(element): I don't know why I am getting this error. Can anyone help. Thank you.

f = open ('testLC31.txt', 'r')
lineCount = 0

toIgnore = ["AND", "ADD", "LEA", "PUTS", "JSR", "LD", "JSRR" , "NOT", "LDI" ,
            "LDR", "ST", "STI", "STR", "BR" , "JMP", "TRAP" , "JMP", "RTI" ,
            "BR", "ST", "STI" , "STR" , "BRz", "BRn" , "HALT"]

label = []
instructions = []
i = 0

for line in f:
    line = line.split()

    for element in toIgnore:
        if line[0].startswith(element):
            lineCount += 1
        else:
            label.append(line[0])
            instructions.append(line[1])
            i += 1
            lineCount += 1

SAMPLE FILE:

.ORIG x3000

     AND    R0, R0, #0        
     AND    R1, R1, #0        
     AND    R2, R2, #0        
     AND    R7, R7, #0        

     LEA    R0, MSG1          
     PUTS                     

     LEA    R1, MEMORYSPACE   

     JSR    STRNG             

     LD     R0, NEWLINE
     OUT

     ADD    R0, R1, #0        
     LD     R2, NEG48         
     ADD    R0, R0, R2        
     PUTS                     

     HALT

     MSG1          .STRINGZ   "Input a string (length <= 9): "
     MEMORYSPACE   .BLKW      9
     NEWLINE       .FILL      #10
     NEG48         .FILl      #-48

          .END

Answer 1

there are a few issues with this, I don't know what your requirement is so this is one approach.. but you are adding the exact same word for every instance that its not in the ignore list so there will be a LOT of duplicates. if you want that removed let me know and I can add that for you

for line in f:
    if line.split(): #check to see if it is actually something that can be split
        elem = line.split()
        if len(elem) > 1: #check to see that its more than one word if its not then you are on one of the ignore words
            for element in toIgnore:
                if elem[0].startswith(element):
                    lineCount += 1
                else:
                    label.append(elem[0])
                    instructions.append(elem[1])
                    i += 1
                    lineCount += 1

if you want to have unique instructions in your list then you can just do this

f = open ('testLC31.txt', 'r')
line_count = 0

to_ignore = ["AND", "ADD", "LEA", "PUTS", "JSR", "LD", "JSRR" , "NOT", "LDI" ,
            "LDR", "ST", "STI", "STR", "BR" , "JMP", "TRAP" , "JMP", "RTI" ,
            "BR", "ST", "STI" , "STR" , "BRz", "BRn" , "HALT"]

label = []
instructions = []
i = 0
for line in f:
    elem = line.split() if line.split() else ['']
    if len(elem) > 1 and elem[0] not in to_ignore:
        label.append(elem[0])
        instructions.append(elem[1])
        i += 1
        line_count += 1
    elif elem[0] in to_ignore:
        line_count += 1

Answer 2

The reason you get an index out of range error is that "".split() results in an empty list []. Thus when an empty line is read, it leads to an empty list line, and list[0] results in an out of range error.