A blog about coding
Sometimes the file that is read by xmgrace has a header like below:
Ratio
0.67
0.52
...If use xmgrace directly, we cannot plot the curve as expected.
I haven’t found the way of using xmgrace only. Instead, I only found how to specify columns using xmgrace.
With the help of other tools, here is a way to work around.
tail -n +2 a.txt | xmgrace -pipeor
sed 1d a.txt | xmgrace -pipeFirewalld is a firewall management solution provided by Linux.
Check if firewalld is running:
sudo firewall-cmd --state
runningDisable firewalld:
sudo systemctl disable --now firewalldCheck its state again:
sudo firewall-cmd --state
not runningEnable firewalld:
sudo systemctl disable --now firewalld
or
sudo /usr/sbin/firewalldCRTP (Curiously Recurring Template Pattern) is a very useful skill to achieve static polymorphism.
How to achieve CRTP if the derived class is a template class? Here is an example.
#include <iostream>
#include <string>
using namespace std;
// Base class A
template< typename Type, template< typename > class Derived >
class A {
public:
A() = default;
virtual ~A() = default;
void output( Type num ) {
cout << "From base A, ";
static_cast< Derived< Type > * > (this)->speak( num );
}
protected:
virtual void speak( Type num ) = 0;
};
// Derived class B, override the protected method speak()
template< typename Type >
class B : public A< Type, B > {
friend class A< Type, B >;
public:
using A< Type, B >::A;
protected:
void speak( Type num ) override {
cout << "I am B, and I got " << std::to_string( num ) << endl;
}
};
// Derived class C, override the protected method speak()
template< typename Type >
class C : public A< Type, C > {
friend class A< Type, C >;
public:
using A< Type, C >::A;
protected:
void speak( Type num ) override {
cout << "I am C, and I got " << std::to_string( num ) << endl;
}
};
// Client code
int main(int argc, char** argv) {
B< float > b;
b.output( 5 );
C< float > c;
c.output( 8 );
return 0;
}
Use g++ to compile the above code, and get the outputs.
g++ -o crtptest main.cpp --std=c++14
./crtptest
From base A, I am B, and I got 5.000000
From base A, I am C, and I got 8.000000A simple way to read a whole file into a std::string.
#include <fstream>
#include <sstream>
...
std::ifstream file( "a.txt" );
std::stringstream buffer;
buffer << file.rdbuf();
std::string content = buffer.str();