How can I go to the next line in .txt file?

How can I read only first symbol in each line with out reading all line, using python? For example, if I have file like:

apple  
pear  
watermelon 

In each iteration I must store only one (the first) letter of line. Result of program should be ["a","p","w"], I tried to use file.seek(), but how can I move it to the new line?

Answer

file-like objects are iterable, so you can directly use them like this

collection = []

with open("input.txt") as fh:
    for line in fh:  # iterate by-lines over file-like
        try:
            collection.append(line[0])  # get the first char in the line
        except IndexError:  # line has no chars
            pass  # consider other handling

# work with collection

You may also consider enumerate() if you cared about which line a particular value was on, or yielding line[0] to form a generator (which may allow a more efficient process if it can halt before reading the entire file)

def my_generator():
    with open("input.txt") as fh:
        for lineno, line in enumerate(fh, 1):  # lines are commonly 1-indexed
            try:
                yield lineno, line[0]  # first char in the line
            except IndexError:  # line has no chars
                pass  # consider other handling

for lineno, first_letter in my_generator():
    # work with lineno and first_letter here and break when done