如何检查文件的每一行是否以空格开头？

Question

I'm trying to create a function that iterates through each line of a code file and checks to see if each line starts white a whitespace.

  # open file for reading
file = open('FileHandle', 'r')

# iterates through each line in file 
for aline in file.readlines():
    # splits each line in file into a separate line
    values = aline.split()
    # removes whitespaces that have been unintentionally added
    values = aline.rstrip() 
    # iterates through each line in file
    for values in aline:
        if values.startswith(' ') == True:
            # the first chacter is a space
            print 'Contains a line that starts with a space.'
        # checks if first character is something other than a space
        if values.startswith(' ') == False:
            # the first character is something other than a space
            # since blank lines contain no characters (not even spaces), this will still
            # be true boolean since '' is not == to ' '. 
            print 'Lines in file do not start with whitespace.'

I keep just getting multiple printed statements instead of a single concise statement, even if 1 line starts with a whitespace to print 'Contains a line that starts with a space.'. I'm assuming this has to do with that that my print statements are in the loop.

Answer 1

The problem is because you are printing from within the loop. Instead, you can store the results in a variable and print after the loop:

has_line_starting_with_space = False
for values in aline:
    if values.startswith(' '):
        has_line_starting_with_space = True
        # no need to continue processing
        break
if has_line_starting_with_space:
    print 'Contains a line that starts with a space.'
else:
    print 'Lines in file do not start with whitespace.'

Note: this only handles space character and not other types of whitespace such as tabs. To cover those cases, you can use the re module.

Answer 2

Its pretty simple..All you have to do is Just check the if condition only with startswith function, You don't need that should check with "== true"..

Code is:

with open("file","r") as readfile:
    for line in readfile:
        if line.startswith( ' ' ):
            print "Contains a line that starts with a space."
        else:
            print "Lines in file do not start with whitespace."