在另一个用户定义的函数中调用用户定义的函数时发生Nameerror

Question

I need to write a program that opens and reads a file and contains separate user-defined functions for counting the number of lines and words in the file eg linecount(), wordcount()etc. I drafted the below code, but I keep getting a name error that says "global name 'f' is not defined". f is a file handle that should be returned by the openfile() function. Any advise?

#open and read file
def openfile():
    import string
    name = raw_input ("enter file name: ")
    f = open (name)

# Calculates the number of paragraphs within the file 
def linecount():
    openfile()
    lines = 0
    for line in f:
        lines = lines + 1
    return lines

#call function that counts lines
linecount()

Answer 1

Because f is local variable in openfile

def openfile():
    import string
    name = raw_input ("enter file name: ")
    return open (name)

# Calculates the number of paragraphs within the file 
def linecount():
    f = openfile()
    lines = 0
    for line in f:
        lines = lines + 1
    return lines

or even shorter

def file_line_count():
    file_name = raw_input("enter file name: ")
    with open(file_name, 'r') as f:
        return sum(1 for line in f)