from sys import argv

script, input_file = argv

# 定義print_all函數(shù)
def print_all(f):
    # 打印文件全部內容
    print(f.read())

# 定義函數(shù)rewind,參數(shù)f引用文件對象
def rewind(f):
    # f。seek(0)是讓基準點回到開始位置
    # 如果是seek(1),那就是讓基準點回到當前位置
    # 如果是seek(2),那就是讓基準點回到結束為止
    f.seek(0)

# 定義函數(shù)print_a_line,參數(shù)line_count和f都是引用文件對象的
def print_a_line(line_count, f):
    #f.readline()是一行一行讀取的
    print(line_count, f.readline())

#  把文件input_file對象賦值給current_file
current_file = open(input_file)

# 打印
print("First let's print the whole file:\n")

# 調用函數(shù)print_all
print_all(current_file)

# 打印
print("Now let's rewind, kind of like a tape.")

# 調用函數(shù)rewind,作用就和倒帶差不多
rewind(current_file)

# 打印
print("Let's print three lines:")

# 把1賦值給current_line
current_line = 1
# 調用函數(shù)print_a_line
print_a_line(current_line, current_file)

# current_line自增
current_line = current_line + 1
# 調用print_a_line函數(shù)
print_a_line(current_line, current_file)

# 自增
current_line = current_line + 1
# 調用函數(shù)print_a_line
print_a_line(current_line, current_file)

第一次print_a_line被調用, current_line被賦值1
第二次print_a_line被調用, current_line被賦值2
第三次print_a_line被調用, current_line被賦值3

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5.點擊