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How do I check if there are duplicates in a flat list?
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Use set() to remove duplicates if all values are hashable:
>>> your_list = ['one', 'two', 'one']
>>> len(your_list) != len(set(your_list))
True
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How do I find the location of my Python site-packages directory?
...ib"])'
The per user site-packages directory (PEP 370) is where Python installs your local packages:
python -m site --user-site
If this points to a non-existing directory check the exit status of Python and see python -m site --help for explanations.
Hint: Running pip list --user or pip freeze -...
Number of elements in a javascript object
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Although JS implementations might keep track of such a value internally, there's no standard way to get it.
In the past, Mozilla's Javascript variant exposed the non-standard __count__, but it has been removed with version 1.8.5.
For cross-browser scripting you're stuck with explicitly ite...
C Macro definition to determine big endian or little endian machine?
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Code supporting arbitrary byte orders, ready to be put into a file called order32.h:
#ifndef ORDER32_H
#define ORDER32_H
#include <limits.h>
#include <stdint.h>
#if CHAR_BIT != 8
#error "unsupported char size"
#endif
enum
{
O32_LITTLE_ENDIAN = 0x03020100ul,
O32_BIG_END...
OceanBase使用libeasy原理源码分析：服务器端 - 数据库(内核) - 清泛网 - ...
...nection_t(TCP连接)的输出缓冲区链表中
handler_.encode = ObMySQLCallback::encode;
// libeasy回调这个函数用于从该连接的输入缓冲区中反序列化出一个符合MySQL协议的包，然后吐给上层使用
handler_.decode = ObMySQLCallback::decode;
// 对于每个decode...
Using the Underscore module with Node.js
...rom Underscore, it overwrites the _ object with the result of my function call. Anyone know what's going on? For example, here is a session from the node.js REPL:
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How to list all installed packages and their versions in Python?
Is there a way in Python to list all installed packages and their versions?
11 Answers
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JRE 1.7 - java version - returns: java/lang/NoClassDefFoundError: java/lang/Object
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This problem stems from an improper Java installation.
Possibility 1
NOTE: This scenario only applies to Java 8 and prior. Beginning with Java 9, the JRE is structured differently. rt.jar and friends no longer exist, and Pack200 is no longer used.
The Java standa...
Why #define TRUE (1==1) in a C boolean macro instead of simply as 1?
...type (and resolve to true and false) if the compiler supports it. (specifically, C++)
However, it would be better to check whether C++ is in use (via the __cplusplus macro) and actually use true and false.
In a C compiler, this is equivalent to 0 and 1.
(note that removing the parentheses will bre...
How do I find the location of Python module sources?
How do I learn where the source file for a given Python module is installed? Is the method different on Windows than on Linux?
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