python print'hello' File "<stdin>",line 1 print 'hello' SyntaxError:invalid syntax

本文介绍Python 3.0中print语句的变化,即从print语句更改为print()函数,并提供正确的使用示例。对于初学者而言,了解这一变化有助于避免语法错误。

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python print'hello' File "<stdin>",line 1 print 'hello' SyntaxError:invalid syntax

刚开始看Python,照着书上些了个hello,结果错误:

>>> print 'hello'
  File "<stdin>", line 1
    print 'hello'
                ^
SyntaxError: invalid syntax

 

查看3.0文档:http://docs.python.org/release/3.0.1/whatsnew/3.0.html,发现从3.0开始print改成了

print()。文档是这样写的:The print statement has been replaced with a print() function, with keyword arguments to replace most of the special syntax of the old print statement (PEP 3105).

print语句被print()方法代替,旧print语句中的特定的语法被参数代替。

所以呢,hello world!应该写成这样:print ("hello world!")


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>>> import torch >>> >>> a = torch.randn(10000, 10000) # 在CPU创建张量 File "<stdin>", line 1 >>> a = torch.randn(10000, 10000) # 在CPU创建张量 ^^ SyntaxError: invalid syntax >>> Traceback (most recent call last): File "<stdin>", line 1 Traceback (most recent call last): ^^^^^^^^^^^ SyntaxError: invalid syntax. Perhaps you forgot a comma? >>> File "<stdin>", line 1, in <module> File "<stdin>", line 1 File "<stdin>", line 1, in <module> IndentationError: unexpected indent >>> NameError: name 'torch' is not defined File "<stdin>", line 1 NameError: name 'torch' is not defined ^^^^^^^ SyntaxError: invalid syntax >>> >>> b = torch.randn(10000, 10000) File "<stdin>", line 1 >>> b = torch.randn(10000, 10000) ^^ SyntaxError: invalid syntax >>> Traceback (most recent call last): File "<stdin>", line 1 Traceback (most recent call last): ^^^^^^^^^^^ SyntaxError: invalid syntax. Perhaps you forgot a comma? >>> File "<stdin>", line 1, in <module> File "<stdin>", line 1 File "<stdin>", line 1, in <module> IndentationError: unexpected indent >>> NameError: name 'torch' is not defined File "<stdin>", line 1 NameError: name 'torch' is not defined ^^^^^^^ SyntaxError: invalid syntax >>> >>> File "<stdin>", line 1 >>> ^^ SyntaxError: invalid syntax >>> >>> # GPU版本 File "<stdin>", line 1 >>> # GPU版本 ^^ SyntaxError: invalid syntax >>> >>> a_cuda = a.cuda() File "<stdin>", line 1 >>> a_cuda = a.cuda() ^^ SyntaxError: invalid syntax >>> Traceback (most recent call last): File "<stdin>", line 1 Traceback (most recent call last): ^^^^^^^^^^^ SyntaxError: invalid syntax. Perhaps you forgot a comma? >>> File "<stdin>", line 1, in <module> File "<stdin>", line 1 File "<stdin>", line 1, in <module> IndentationError: unexpected indent >>> NameError: name 'a' is not defined File "<stdin>", line 1 NameError: name 'a' is not defined ^^^ SyntaxError: invalid syntax >>> >>> b_cuda = b.cuda() File "<stdin>", line 1 >>> b_cuda = b.cuda() ^^ SyntaxError: invalid syntax >>> Traceback (most recent call last): File "<stdin>", line 1 Traceback (most recent call last): ^^^^^^^^^^^ SyntaxError: invalid syntax. Perhaps you forgot a comma? >>> File "<stdin>", line 1, in <module> File "<stdin>", line 1 File "<stdin>", line 1, in <module> IndentationError: unexpected indent >>> NameError: name 'b' is not defined File "<stdin>", line 1 NameError: name 'b' is not defined ^^^ SyntaxError: invalid syntax >>> >>> %timeit a_cuda @ b_cuda # 应获得明显加速
04-01
Type "help", "copyright", "credits" or "license" for more information. >>> MvCamera.MV_CC_Initialize() Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'MvCamera' is not defined >>> MvCamera.MV_CC_Initialize() Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'MvCamera' is not defined >>> cd d:/海康/MVS/Development/Samples/Python/MvImport File "<stdin>", line 1 cd d:/海康/MVS/Development/Samples/Python/MvImport ^ SyntaxError: invalid syntax >>> & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py File "<stdin>", line 1 & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py ^ SyntaxError: invalid syntax >>> cd d:/海康/MVS/Development/Samples/Python/MvImport File "<stdin>", line 1 cd d:/海康/MVS/Development/Samples/Python/MvImport ^ SyntaxError: invalid syntax >>> & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py File "<stdin>", line 1 & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py ^ SyntaxError: invalid syntax >>> cd d:/海康/MVS/Development/Samples/Python/MvImport File "<stdin>", line 1 cd d:/海康/MVS/Development/Samples/Python/MvImport ^ SyntaxError: invalid syntax >>> & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py File "<stdin>", line 1 & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py ^ SyntaxError: invalid syntax >>> cd d:/海康/MVS/Development/Samples/Python/MvImport File "<stdin>", line 1 cd d:/海康/MVS/Development/Samples/Python/MvImport ^ SyntaxError: invalid syntax >>> & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py File "<stdin>", line 1 & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py ^ SyntaxError: invalid syntax >>> cd d:/海康/MVS/Development/Samples/Python/MvImport File "<stdin>", line 1 cd d:/海康/MVS/Development/Samples/Python/MvImport ^ SyntaxError: invalid syntax >>> & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py File "<stdin>", line 1 & D:/python/python.exe d:/海康/MVS/Development/Samples/Python/MvImport/3.py ^ SyntaxError: invalid syntax
07-10
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