CODEWITHSUNDEEP
pythonstringpython-3.x
Justen
Justen

Reputation: 4869

str.startswith() not working as I intended

I'm trying to test for a /t or a space character and I can't understand why this bit of code won't work. What I am doing is reading in a file, counting the loc for the file, and then recording the names of each function present within the file along with their individual lines of code. The bit of code below is where I attempt to count the loc for the functions.

import re

...
    else:
            loc += 1
            for line in infile:
                line_t = line.lstrip()
                if len(line_t) > 0 \
                and not line_t.startswith('#') \
                and not line_t.startswith('"""'):
                    if not line.startswith('\s'):
                        print ('line = ' + repr(line))
                        loc += 1
                        return (loc, name)
                    else:
                        loc += 1
                elif line_t.startswith('"""'):
                    while True:
                        if line_t.rstrip().endswith('"""'):
                            break
                        line_t = infile.readline().rstrip()

            return(loc,name)

Output:

Enter the file name: test.txt
line = '\tloc = 0\n'

There were 19 lines of code in "test.txt"

Function names:

    count_loc -- 2 lines of code

As you can see, my test print for the line shows a /t, but the if statement explicitly says (or so I thought) that it should only execute with no whitespace characters present.

Here is my full test file I have been using:

def count_loc(infile):
    """ Receives a file and then returns the amount
        of actual lines of code by not counting commented
        or blank lines """

    loc = 0
    for line in infile:
        line = line.strip()
        if len(line) > 0 \
        and not line.startswith('//') \
        and not line.startswith('/*'):
            loc += 1
            func_loc, func_name = checkForFunction(line);
        elif line.startswith('/*'):
            while True:
                if line.endswith('*/'):
                    break
                line = infile.readline().rstrip()

    return loc

 if __name__ == "__main__":
    print ("Hi")
    Function LOC = 15
    File LOC = 19

Upvotes: 1

Views: 6014

Answers (3)

stephan
stephan

Reputation: 10265

Your question has already been answered and this is slightly off-topic, but...

If you want to parse code, it is often easier and less error-prone to use a parser. If your code is Python code, Python comes with a couple of parsers (tokenize, ast, parser). For other languages, you can find a lot of parsers on the internet. ANTRL is a well-known one with Python bindings.

As an example, the following couple of lines of code print all lines of a Python module that are not comments and not doc-strings:

import tokenize

ignored_tokens = [tokenize.NEWLINE,tokenize.COMMENT,tokenize.N_TOKENS
                 ,tokenize.STRING,tokenize.ENDMARKER,tokenize.INDENT
                 ,tokenize.DEDENT,tokenize.NL]
with open('test.py', 'r') as f:
    g = tokenize.generate_tokens(f.readline)
    line_num = 0
    for a_token in g:
        if a_token[2][0] != line_num and a_token[0] not in ignored_tokens:
            line_num = a_token[2][0]
            print(a_token)

As a_token above is already parsed, you can easily check for function definition, too. You can also keep track where the function ends by looking at the current column start a_token[2][1]. If you want to do more complex things, you should use ast.

Upvotes: 3

Mr_Pink
Mr_Pink

Reputation: 109404

You string literals aren't what you think they are. You can specify a space or TAB like so:

space = ' '
tab = '\t'

Upvotes: 2

S.Lott
S.Lott

Reputation: 391852

\s is only whitespace to the re package when doing pattern matching.

For startswith, an ordinary method of ordinary strings, \s is nothing special. Not a pattern, just characters.

Upvotes: 8

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