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各编程语言读写文件汇总 - C/C++ - 清泛网 - 专注C/C++及内核技术
...ILE *fp = fopen("test.txt", "r");
// 把指针移动到文件的结尾，使用ftell获取文件长度
fseek(fp, 0 ,SEEK_END);
int len = ftell(fp);
// 定义数组长度
char *pBuf = new char[len + 1];
// 把指针移动到文件开头，因为我们一开始把指针移动到了结尾...
Rails: Default sort order for a rails model?
...efault_scope { order(created_at: :desc) } if, like me, you try to minimize sql syntax in rails.<br/>If you have multiple columns to order by and you want to use the new syntax you may need to wrap the desc columns in mustaches like this default_scope { order({begin_date: :desc}, :name) }
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Is there a software-engineering methodology for functional programming? [closed]
...elational definition of the essential state in clojure without reinventing sql (without its flaws)? Or is the idea to simply use a good relational (sql) DB and built a functional program on top of it without the conceptual mismatch introduced by OOP?
– Thorsten
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What's the false operator in C# good for?
...ample >0 for true, <0 for false and ==0 for null, and then you'd get SQL-style null semantics. You would also have to implement a .IsNull method or property in order that nullity could be checked explicitly.
Comparing to SQL, imagine a table Table with 3 rows with value Foo set to true, 3 ro...
What is Normalisation (or Normalization)?
...y a number. A higher number means fewer redundancies and dependencies. Any SQL table is in 1NF (first normal form, pretty much by definition) Normalizing means changing the schema (often partitioning the tables) in a reversible way, giving a model which is functionally identical, except with less re...
互联网造车运动 - 资讯 - 清泛网 - 专注C/C++及内核技术
...其核心技术在于自主设计的底盘和电池控制系统，从最初使用莲花Elise底盘到自主设计，这期间历时长达十年之久，此外，特斯拉还学习了丰田的质量控制和问题追溯体系，还有奔驰的测试流程，传统汽车企业的支持是特斯拉成...
Best way to select random rows PostgreSQL
I want a random selection of rows in PostgreSQL, I tried this:
12 Answers
12
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Is there a REAL performance difference between INT and VARCHAR primary keys?
...performance difference between using INT vs. VARCHAR as a primary key in MySQL? I'd like to use VARCHAR as the primary key for reference lists (think US States, Country Codes) and a coworker won't budge on the INT AUTO_INCREMENT as a primary key for all tables.
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How to choose the id generation strategy when using JPA and Hibernate
...ble. Do not use in a cluster.
identity
supports identity columns in DB2, MySQL, MS SQL Server, Sybase and HypersonicSQL. The returned identifier is of type long, short or int.
sequence
uses a sequence in DB2, PostgreSQL, Oracle, SAP DB, McKoi or a generator in Interbase. The returned identifier is o...
Reference - What does this error mean in PHP?
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Warning: mysql_fetch_array() expects parameter 1 to be resource, boolean given
First and foremost:
Please, don't use mysql_* functions in new code. They are no longer maintained and are officially deprecated. See the red box? Learn...