State in React components is essential to manage and communicate data in your application. It is represented as a JavaScript object and has component level scope, it can be thought of as the private data of your component.
In the example below we are defining some initial state in the constructor f...
If no ordering function is passed, std::sort will order the elements by calling operator< on pairs of elements, which must return a type contextually convertible to bool (or just bool). Basic types (integers, floats, pointers etc) have already build in comparison operators.
We can overload this ...
// Include sequence containers
#include <vector>
#include <deque>
#include <list>
// Insert sorting algorithm
#include <algorithm>
class Base {
public:
// Constructor that set variable to the value of v
Base(int v): variable(v) {
}
i...
C++11
// Include sequence containers
#include <vector>
#include <deque>
#include <list>
#include <array>
#include <forward_list>
// Include sorting algorithm
#include <algorithm>
class Base {
public:
// Constructor that set variable to the va...
To add a new unique column email to users, run the following command:
rails generate migration AddEmailToUsers email:string:uniq
This will create the following migration:
class AddEmailToUsers < ActiveRecord::Migration[5.0]
def change
add_column :users, :email, :string
add_index...
BigInteger is in an immutable object, so you need to assign the results of any mathematical operation, to a new BigInteger instance.
Addition:
10 + 10 = 20
BigInteger value1 = new BigInteger("10");
BigInteger value2 = new BigInteger("10");
BigInteger sum = value1.add(value...
Model with ForeignKey
We will work with these models :
from django.db import models
class Book(models.Model):
name= models.CharField(max_length=50)
author = models.ForeignKey(Author)
class Author(models.Model):
name = models.CharField(max_length=50)
Suppose we often (always) access ...
You can access each property that belongs to an object with this loop
for (var property in object) {
// always check if an object has a property
if (object.hasOwnProperty(property)) {
// do stuff
}
}
You should include the additional check for hasOwnProperty because an o...
It is undefined behavior to access an index that is out of bounds for an array (or standard library container for that matter, as they are all implemented using a raw array):
int array[] = {1, 2, 3, 4, 5};
array[5] = 0; // Undefined behavior
It is allowed to have a pointer pointing to the en...
pip may be used to install BeautifulSoup. To install Version 4 of BeautifulSoup, run the command:
pip install beautifulsoup4
Be aware that the package name is beautifulsoup4 instead of beautifulsoup, the latter name stands for old release, see old beautifulsoup
Here is an example class which has a couple of instance variables, without using properties:
@interface TestClass : NSObject {
NSString *_someString;
int _someInt;
}
-(NSString *)someString;
-(void)setSomeString:(NSString *)newString;
-(int)someInt;
-(void)setSomeInt:(NSString *)...
Assuming a source file of hello_world.v and a top level module of hello_world. The code can be run using various simulators. Most simulators are compiled simulators. They require multiple steps to compile and execute.
Generally the
First step is to compile the Verilog design.
Second step is to ...
The syntax for Java generics bounded wildcards, representing the unknown type by ? is:
? extends T represents an upper bounded wildcard. The unknown type represents a type that must be a subtype of T, or type T itself.
? super T represents a lower bounded wildcard. The unknown type repres...
For programmers coming from GCC or Clang to Visual Studio, or programmers more comfortable with the command line in general, you can use the Visual C++ compiler from the command line as well as the IDE.
If you desire to compile your code from the command line in Visual Studio, you first need to set...
When using labels, both the start and the stop are included in the results.
import pandas as pd
import numpy as np
np.random.seed(5)
df = pd.DataFrame(np.random.randint(100, size=(5, 5)), columns = list("ABCDE"),
index = ["R" + str(i) for i in range(5)])
...
DataFrame:
import pandas as pd
import numpy as np
np.random.seed(5)
df = pd.DataFrame(np.random.randint(100, size=(5, 5)), columns = list("ABCDE"),
index = ["R" + str(i) for i in range(5)])
df
Out[12]:
A B C D E
R0 99 78 61 16 73...
Group by one column
Using the following DataFrame
df = pd.DataFrame({'A': ['a', 'b', 'c', 'a', 'b', 'b'],
'B': [2, 8, 1, 4, 3, 8],
'C': [102, 98, 107, 104, 115, 87]})
df
# Output:
# A B C
# 0 a 2 102
# 1 b 8 98
# 2 c 1 107
# 3 a...
