• 现象： 不管是输入命令 init 3 或者 init5 ，重启后都是直接进入图形界面...# inittab is no longer used when using systemd. # # ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM. # # Ctrl-Alt-D...
现象：
不管是输入命令 init 3 或者 init5 ，重启后都是直接进入图形界面vim /etc/inittab 查看，内容如下：
# inittab is no longer used when using systemd.
#
#
# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
#
# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
#
# multi-user.target: analogous to runlevel 3
# graphical.target: analogous to runlevel 5
#
# To view current default target, run:
# systemctl get-default
#
# To set a default target, run:
# systemctl set-default TARGET.target

解决方案：
英文注释写的很清楚，大致就是用systemctl set-default   和 systemctl get-default 取代数字级别 # 查看当前运行级别
systemctl get-default

# 设置当前运行级别为3 （开机为命令行模式）
systemctl set-default multi-user.target

# 设置当前运行级别为5 （开机为图形界面）
systemctl set-default graphical.target   
展开全文
• 参考：https://unix.stackexchange.com/questions/507131/openssl-1-1-1b-warning-using-iter-or-pbkdf2-would-be-better-while-decrypting 加上-pbkdf2即可。 openssl aes-256-cbc -salt -pbkdf2 -in name -out ...
参考：https://unix.stackexchange.com/questions/507131/openssl-1-1-1b-warning-using-iter-or-pbkdf2-would-be-better-while-decrypting
加上-pbkdf2即可。
openssl aes-256-cbc -salt -pbkdf2 -in name -out name.aes

openssl aes-256-cbc -d -salt -pbkdf2 -in name.aes -out name

但是要注意没有用-pbkdf2加密的文件不能用-pbkdf2选项解密。
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• 版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接本声明。 ...


版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。

本文链接：
https://blog.csdn.net/fpcc/article/details/54582670

在普通的类型名定义时，理论上讲二者是没有区别的，标准上是这样说的：
A typedef-name can also be introduced by analias-declaration. The identifier following the using keyword becomes atypedef-name and the optional attribute-specifier-seq following the identifierappertains to that typedef-name. It has the same semantics as if it wereintroduced by the typedef specifier. In particular, it does not define a newtype and it shall not appear in the type-id
类似于#define和typedef，举例如下：
using WorkerProc= std::function<void(T*)>;
typedef std::function<void(T*)>  WorkerProc;
上面也提到了，二者是等价的。
但也是有一些细微的区别的,从网上找了个例子
// type alias can introduce a member typedef name
template<typename T>
struct Container {
using value_type = T;
};
// which can be used in generic programming
template<typename Container>
void fn2(const Container& c)
{
typenameContainer::value_type n;
}
// 2016/08/25 补
int main()
{
Container<int> c;
fn2(c); // Container::value_type will be int in this function
return 0;
}
红色的部分显示的表明这是一个类型名，而不是一个静态成员变量，否则会误认为其是一个静态成员变量。这个在Effective C++和C++模板里也有说明。
细节很重要，但还是那句话，不要沉迷于细节。
展开全文
• ## using和typedef区别

千次阅读 2017-01-17 14:19:22
在普通的类型名定义时，理论上讲二者是没有区别的，标准上是这样说的： A typedef-name can also be introduced by analias-declaration. The identifier following the using keyword becomes atypedef-name and ...
在普通的类型名定义时，理论上讲二者是没有区别的，标准上是这样说的：
A typedef-name can also be introduced by analias-declaration. The identifier following the using keyword becomes atypedef-name and the optional attribute-specifier-seq following the identifierappertains to that typedef-name. It has the same semantics as if it wereintroduced by the typedef specifier. In particular, it does not define a newtype and it shall not appear in the type-id
类似于#define和typedef，举例如下：
using WorkerProc= std::function<void(T*)>;
typedef std::function<void(T*)>  WorkerProc;
上面也提到了，二者是等价的。
但也是有一些细微的区别的,从网上找了个例子
// type alias can introduce a member typedef name
template<typename T>
struct Container {
using value_type = T;
};
// which can be used in generic programming
template<typename Container>
void fn2(const Container& c)
{
typename Container::value_type n;
}
// 2016/08/25 补
int main()
{
Container<int> c;
fn2(c); // Container::value_type will be int in this function
return 0;
}
红色的部分显示的表明这是一个类型名，而不是一个静态成员变量，否则会误认为其是一个静态成员变量。这个在Effective C++和C++模板里也有说明。
细节很重要，但还是那句话，不要沉迷于细节。
展开全文
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• Title: Problem Solving in Data Structures & Algorithms Using C++: Programming Interview Guide Language: English Publisher: CreateSpace Independent Publishing Platform Publication Date: 2017-01-08 ISBN...
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