Hướng dẫn the write method() returns in python - phương thức write () trả về trong python

7.1.1. Chuỗi được định dạng theo nghĩa chữFormatted String Literals¶

Các chuỗi chữ được định dạng (còn được gọi là F-Strings viết tắt) cho phép bạn bao gồm giá trị của các biểu thức python bên trong một chuỗi bằng cách tiền tố chuỗi với

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

>>> yes_votes = 42_572_654
>>> no_votes = 43_132_495
>>> percentage = yes_votes / (yes_votes + no_votes)
>>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
' 42572654 YES votes  49.67%'

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

>>> yes_votes = 42_572_654
>>> no_votes = 43_132_495
>>> percentage = yes_votes / (yes_votes + no_votes)
>>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
' 42572654 YES votes  49.67%'

Một định dạng định dạng tùy chọn có thể theo biểu thức. Điều này cho phép kiểm soát nhiều hơn về cách giá trị được định dạng. Các ví dụ sau đây làm tròn Pi đến ba vị trí sau thập phân:

>>> import math
>>> print(f'The value of pi is approximately {math.pi:.3f}.')
The value of pi is approximately 3.142.

Vượt qua một số nguyên sau

>>> yes_votes = 42_572_654
>>> no_votes = 43_132_495
>>> percentage = yes_votes / (yes_votes + no_votes)
>>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
' 42572654 YES votes  49.67%'

>>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
>>> for name, phone in table.items():
...     print(f'{name:10} ==> {phone:10d}')
...
Sjoerd     ==>       4127
Jack       ==>       4098
Dcab       ==>       7678

Các sửa đổi khác có thể được sử dụng để chuyển đổi giá trị trước khi nó được định dạng.

>>> yes_votes = 42_572_654
>>> no_votes = 43_132_495
>>> percentage = yes_votes / (yes_votes + no_votes)
>>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
' 42572654 YES votes  49.67%'

>>> yes_votes = 42_572_654
>>> no_votes = 43_132_495
>>> percentage = yes_votes / (yes_votes + no_votes)
>>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
' 42572654 YES votes  49.67%'

>>> s = 'Hello, world.'
>>> str(s)
'Hello, world.'
>>> repr(s)
"'Hello, world.'"
>>> str(1/7)
'0.14285714285714285'
>>> x = 10 * 3.25
>>> y = 200 * 200
>>> s = 'The value of x is ' + repr(x) + ', and y is ' + repr(y) + '...'
>>> print(s)
The value of x is 32.5, and y is 40000...
>>> # The repr() of a string adds string quotes and backslashes:
... hello = 'hello, world\n'
>>> hellos = repr(hello)
>>> print(hellos)
'hello, world\n'
>>> # The argument to repr() may be any Python object:
... repr((x, y, ('spam', 'eggs')))
"(32.5, 40000, ('spam', 'eggs'))"

>>> year = 2016
>>> event = 'Referendum'
>>> f'Results of the {year} {event}'
'Results of the 2016 Referendum'

>>> s = 'Hello, world.'
>>> str(s)
'Hello, world.'
>>> repr(s)
"'Hello, world.'"
>>> str(1/7)
'0.14285714285714285'
>>> x = 10 * 3.25
>>> y = 200 * 200
>>> s = 'The value of x is ' + repr(x) + ', and y is ' + repr(y) + '...'
>>> print(s)
The value of x is 32.5, and y is 40000...
>>> # The repr() of a string adds string quotes and backslashes:
... hello = 'hello, world\n'
>>> hellos = repr(hello)
>>> print(hellos)
'hello, world\n'
>>> # The argument to repr() may be any Python object:
... repr((x, y, ('spam', 'eggs')))
"(32.5, 40000, ('spam', 'eggs'))"

>>> year = 2016
>>> event = 'Referendum'
>>> f'Results of the {year} {event}'
'Results of the 2016 Referendum'

>>> animals = 'eels'
>>> print(f'My hovercraft is full of {animals}.')
My hovercraft is full of eels.
>>> print(f'My hovercraft is full of {animals!r}.')
My hovercraft is full of 'eels'.

Bộ xác định

>>> s = 'Hello, world.'
>>> str(s)
'Hello, world.'
>>> repr(s)
"'Hello, world.'"
>>> str(1/7)
'0.14285714285714285'
>>> x = 10 * 3.25
>>> y = 200 * 200
>>> s = 'The value of x is ' + repr(x) + ', and y is ' + repr(y) + '...'
>>> print(s)
The value of x is 32.5, and y is 40000...
>>> # The repr() of a string adds string quotes and backslashes:
... hello = 'hello, world\n'
>>> hellos = repr(hello)
>>> print(hellos)
'hello, world\n'
>>> # The argument to repr() may be any Python object:
... repr((x, y, ('spam', 'eggs')))
"(32.5, 40000, ('spam', 'eggs'))"

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Xem các biểu thức tự ghi chép để biết thêm thông tin về trình xác định

>>> s = 'Hello, world.'
>>> str(s)
'Hello, world.'
>>> repr(s)
"'Hello, world.'"
>>> str(1/7)
'0.14285714285714285'
>>> x = 10 * 3.25
>>> y = 200 * 200
>>> s = 'The value of x is ' + repr(x) + ', and y is ' + repr(y) + '...'
>>> print(s)
The value of x is 32.5, and y is 40000...
>>> # The repr() of a string adds string quotes and backslashes:
... hello = 'hello, world\n'
>>> hellos = repr(hello)
>>> print(hellos)
'hello, world\n'
>>> # The argument to repr() may be any Python object:
... repr((x, y, ('spam', 'eggs')))
"(32.5, 40000, ('spam', 'eggs'))"

>>> s = 'Hello, world.'
>>> str(s)
'Hello, world.'
>>> repr(s)
"'Hello, world.'"
>>> str(1/7)
'0.14285714285714285'
>>> x = 10 * 3.25
>>> y = 200 * 200
>>> s = 'The value of x is ' + repr(x) + ', and y is ' + repr(y) + '...'
>>> print(s)
The value of x is 32.5, and y is 40000...
>>> # The repr() of a string adds string quotes and backslashes:
... hello = 'hello, world\n'
>>> hellos = repr(hello)
>>> print(hellos)
'hello, world\n'
>>> # The argument to repr() may be any Python object:
... repr((x, y, ('spam', 'eggs')))
"(32.5, 40000, ('spam', 'eggs'))"

7.1.2. Phương thức định dạng chuỗi ()The String format() Method¶

Việc sử dụng cơ bản của phương thức

>>> year = 2016
>>> event = 'Referendum'
>>> f'Results of the {year} {event}'
'Results of the 2016 Referendum'

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Các dấu ngoặc và ký tự trong chúng (được gọi là trường định dạng) được thay thế bằng các đối tượng được truyền vào phương thức

>>> year = 2016
>>> event = 'Referendum'
>>> f'Results of the {year} {event}'
'Results of the 2016 Referendum'

>>> year = 2016
>>> event = 'Referendum'
>>> f'Results of the {year} {event}'
'Results of the 2016 Referendum'

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Nếu các đối số từ khóa được sử dụng trong phương thức

>>> year = 2016
>>> event = 'Referendum'
>>> f'Results of the {year} {event}'
'Results of the 2016 Referendum'

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Đối số vị trí và từ khóa có thể được kết hợp một cách tùy ý:

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Nếu bạn có một chuỗi định dạng thực sự dài mà bạn không muốn chia tách, sẽ thật tuyệt nếu bạn có thể tham khảo các biến được định dạng theo tên thay vì theo vị trí. Điều này có thể được thực hiện bằng cách đơn giản là vượt qua Dict và sử dụng dấu ngoặc vuông

>>> import math
>>> print(f'The value of pi is approximately {math.pi:.3f}.')
The value of pi is approximately 3.142.

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Điều này cũng có thể được thực hiện bằng cách truyền từ điển

>>> import math
>>> print(f'The value of pi is approximately {math.pi:.3f}.')
The value of pi is approximately 3.142.

>>> import math
>>> print(f'The value of pi is approximately {math.pi:.3f}.')
The value of pi is approximately 3.142.

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Điều này đặc biệt hữu ích khi kết hợp với hàm tích hợp

>>> import math
>>> print(f'The value of pi is approximately {math.pi:.3f}.')
The value of pi is approximately 3.142.

Ví dụ, các dòng sau đây tạo ra một tập hợp các cột được căn chỉnh gọn gàng cho các số nguyên và hình vuông và hình khối của chúng:

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Để biết tổng quan đầy đủ về định dạng chuỗi với

>>> year = 2016
>>> event = 'Referendum'
>>> f'Results of the {year} {event}'
'Results of the 2016 Referendum'

7.1.3. Định dạng chuỗi thủ côngManual String Formatting¶

Ở đây, cùng một bảng hình vuông và hình khối, được định dạng bằng tay:

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

(Lưu ý rằng một không gian giữa mỗi cột được thêm vào bằng cách

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Phương pháp

>>> import math
>>> print(f'The value of pi is approximately {math.pi:.3f}.')
The value of pi is approximately 3.142.

>>> import math
>>> print(f'The value of pi is approximately {math.pi:.3f}.')
The value of pi is approximately 3.142.

>>> import math
>>> print(f'The value of pi is approximately {math.pi:.3f}.')
The value of pi is approximately 3.142.

Có một phương pháp khác,

>>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
>>> for name, phone in table.items():
...     print(f'{name:10} ==> {phone:10d}')
...
Sjoerd     ==>       4127
Jack       ==>       4098
Dcab       ==>       7678

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

7.1.4. Định dạng chuỗi cũOld string formatting¶

Toán tử % (modulo) cũng có thể được sử dụng cho định dạng chuỗi. Cho

>>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
>>> for name, phone in table.items():
...     print(f'{name:10} ==> {phone:10d}')
...
Sjoerd     ==>       4127
Jack       ==>       4098
Dcab       ==>       7678

>>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
>>> for name, phone in table.items():
...     print(f'{name:10} ==> {phone:10d}')
...
Sjoerd     ==>       4127
Jack       ==>       4098
Dcab       ==>       7678

>>> yes_votes = 42_572_654
>>> no_votes = 43_132_495
>>> percentage = yes_votes / (yes_votes + no_votes)
>>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
' 42572654 YES votes  49.67%'

>>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
>>> for name, phone in table.items():
...     print(f'{name:10} ==> {phone:10d}')
...
Sjoerd     ==>       4127
Jack       ==>       4098
Dcab       ==>       7678

#!/usr/bin/python

# Open a file in write mode
fo = open("foo.txt", "rw+")
print "Name of the file: ", fo.name

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

str = "This is 6th line"
# Write a line at the end of the file.
fo.seek(0, 2)
line = fo.write( str )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(6):
   line = fo.next()
   print "Line No %d - %s" % (index, line)

# Close opend file
fo.close()

Thêm thông tin có thể được tìm thấy trong phần định dạng chuỗi kiểu printf.printf-style String Formatting section.

7.2.1. Phương thức của đối tượng tệpMethods of File Objects¶

Phần còn lại của các ví dụ trong phần này sẽ cho rằng một đối tượng tệp được gọi là

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Để đọc nội dung của tệp, hãy gọi

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

#!/usr/bin/python

# Open a file in write mode
fo = open("foo.txt", "rw+")
print "Name of the file: ", fo.name

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

str = "This is 6th line"
# Write a line at the end of the file.
fo.seek(0, 2)
line = fo.write( str )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(6):
   line = fo.next()
   print "Line No %d - %s" % (index, line)

# Close opend file
fo.close()

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

>>> animals = 'eels'
>>> print(f'My hovercraft is full of {animals}.')
My hovercraft is full of eels.
>>> print(f'My hovercraft is full of {animals!r}.')
My hovercraft is full of 'eels'.

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

#!/usr/bin/python

# Open a file in write mode
fo = open("foo.txt", "rw+")
print "Name of the file: ", fo.name

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

str = "This is 6th line"
# Write a line at the end of the file.
fo.seek(0, 2)
line = fo.write( str )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(6):
   line = fo.next()
   print "Line No %d - %s" % (index, line)

# Close opend file
fo.close()

Để đọc các dòng từ một tệp, bạn có thể lặp qua đối tượng tệp. Đây là bộ nhớ hiệu quả, nhanh chóng và dẫn đến mã đơn giản:

#!/usr/bin/python

# Open a file in write mode
fo = open("foo.txt", "rw+")
print "Name of the file: ", fo.name

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

str = "This is 6th line"
# Write a line at the end of the file.
fo.seek(0, 2)
line = fo.write( str )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(6):
   line = fo.next()
   print "Line No %d - %s" % (index, line)

# Close opend file
fo.close()

Nếu bạn muốn đọc tất cả các dòng của một tệp trong danh sách, bạn cũng có thể sử dụng

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

#!/usr/bin/python

# Open a file in write mode
fo = open("foo.txt", "rw+")
print "Name of the file: ", fo.name

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

str = "This is 6th line"
# Write a line at the end of the file.
fo.seek(0, 2)
line = fo.write( str )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(6):
   line = fo.next()
   print "Line No %d - %s" % (index, line)

# Close opend file
fo.close()

Các loại đối tượng khác cần được chuyển đổi - thành một chuỗi (ở chế độ văn bản) hoặc đối tượng byte (ở chế độ nhị phân) - trước khi viết chúng:

#!/usr/bin/python

# Open a file in write mode
fo = open("foo.txt", "rw+")
print "Name of the file: ", fo.name

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

str = "This is 6th line"
# Write a line at the end of the file.
fo.seek(0, 2)
line = fo.write( str )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(6):
   line = fo.next()
   print "Line No %d - %s" % (index, line)

# Close opend file
fo.close()

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Để thay đổi vị trí đối tượng tệp, hãy sử dụng

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

#!/usr/bin/python

# Open a file in write mode
fo = open("foo.txt", "rw+")
print "Name of the file: ", fo.name

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

str = "This is 6th line"
# Write a line at the end of the file.
fo.seek(0, 2)
line = fo.write( str )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(6):
   line = fo.next()
   print "Line No %d - %s" % (index, line)

# Close opend file
fo.close()

Trong các tệp văn bản (những tệp được mở mà không có

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Các đối tượng tệp có một số phương thức bổ sung, chẳng hạn như

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

7.2.2. Lưu dữ liệu có cấu trúc với ________ 132¶Saving structured data with This is 1st line This is 2nd line This is 3rd line This is 4th line This is 5th line 32¶

Chuỗi có thể dễ dàng được ghi và đọc từ một tập tin. Các số cần thêm một chút nỗ lực, vì phương thức

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Thay vì để người dùng liên tục viết và gỡ lỗi mã để lưu các loại dữ liệu phức tạp vào các tệp, Python cho phép bạn sử dụng định dạng trao đổi dữ liệu phổ biến có tên là JSON (ký hiệu đối tượng JavaScript). Mô -đun tiêu chuẩn được gọi là

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Ghi chú

Định dạng JSON thường được sử dụng bởi các ứng dụng hiện đại để cho phép trao đổi dữ liệu. Nhiều lập trình viên đã quen thuộc với nó, điều này làm cho nó trở thành một lựa chọn tốt cho khả năng tương tác.

Nếu bạn có một đối tượng

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Một biến thể khác của hàm

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Để giải mã lại đối tượng, nếu

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Ghi chú

Định dạng JSON thường được sử dụng bởi các ứng dụng hiện đại để cho phép trao đổi dữ liệu. Nhiều lập trình viên đã quen thuộc với nó, điều này làm cho nó trở thành một lựa chọn tốt cho khả năng tương tác.text file for both of reading and writing.

Nếu bạn có một đối tượng

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Một biến thể khác của hàm

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Để giải mã lại đối tượng, nếu

Name of the file:  foo.txt
Line No 0 - This is 1st line

Line No 1 - This is 2nd line

Line No 2 - This is 3rd line

Line No 3 - This is 4th line

Line No 4 - This is 5th line

Line No 5 - This is 6th line

Các tệp JSON phải được mã hóa trong UTF-8. Sử dụng

>>> animals = 'eels'
>>> print(f'My hovercraft is full of {animals}.')
My hovercraft is full of eels.
>>> print(f'My hovercraft is full of {animals!r}.')
My hovercraft is full of 'eels'.