Tutorial by Examples: ar

A value_ptr is a smart pointer that behaves like a value. When copied, it copies its contents. When created, it creates its contents. // Like std::default_delete: template<class T> struct default_copier { // a copier must handle a null T const* in and return null: T* operator()(T co...

Generally, it's not a good idea to use a regular expression to parse a complex structure. But it can be done. For instance, you might want to load data into hive table and fields are separated by comma but complex types like array are separated by a "|". Files contain records with all fiel...

A question that occasionally on StackOverflow is whether it is appropriate to use assert to validate arguments supplied to a method, or even inputs provided by the user. The simple answer is that it is not appropriate. Better alternatives include: Throwing an IllegalArgumentException using cust...

Slices are pointers to arrays, with the length of the segment, and its capacity. They behave as pointers, and assigning their value to another slice, will assign the memory address. To copy a slice value to another, use the built-in copy function: func copy(dst, src []Type) int (returns the amount o...

import sympy as sy x1, x2 = sy.symbols("x1 x2") equations = [ sy.Eq( 2*x1 + 1*x2 , 10 ), sy.Eq( 1*x1 - 2*x2 , 11 ) ] print sy.solve(equations) # Result: {x1: 31/5, x2: -12/5}

import sympy as sy x, y = sy.symbols("x y") # nsolve needs the (in this case: two) equations, the names of the variables # (x,y) we try to evaluate solutions for, and an initial guess (1,1) for the # solution print sy.nsolve((x**3+sy.exp(y)-4,x+3*y),(x,y),(1,1)) The result s...

myfunc(){ echo "I will never be executed." } another_func(){ # this "redeclare" overwrites original function myfunc(){ echo "I am the one and only"; } } # myfunc will print "I will never be executed" myfunc # but if we call another_func fi...

The JAR, WAR and EAR files types are fundamentally ZIP files with a "manifest" file and (for WAR and EAR files) a particular internal directory / file structure. The recommended way to create these files is to use a Java-specific build tool which "understands" the requirements f...

The Oracle Java Tutorials summarize Web Start as follows: Java Web Start software provides the power to launch full-featured applications with a single click. Users can download and launch applications, such as a complete spreadsheet program or an Internet chat client, without going through lengt...

Difference from PHP Array PHP's default Array type is actually implemented as ordered hash maps, which allow us to create arrays that consist of key/value pairs where values can be of any type and keys can be either numbers or strings. This is not traditionally how arrays are created, however. S...

Prerequisites Have a strong grasp of a programming language such as Python, C, C++, Ruby, or any of the other languages out there. Have your favorite code editor or IDE installed (one such example is VSCode) Stay motivated. Constructing a compiler is not easy, so keep pushing; it's worth the ef...

#include <ctype.h> #include <stdio.h> typedef struct { size_t space; size_t alnum; size_t punct; } chartypes; chartypes classify(FILE *f) { chartypes types = { 0, 0, 0 }; int ch; while ((ch = fgetc(f)) != EOF) { types.space += !!isspace(ch); types.al...

#include <ctype.h> #include <stddef.h> typedef struct { size_t space; size_t alnum; size_t punct; } chartypes; chartypes classify(const char *s) { chartypes types = { 0, 0, 0 }; const char *p; for (p= s; p != '\0'; p++) { types.space += !!isspace((unsigned ...

For example, we have two environments: CI - Staging and want to add some customizations for each environment. Here I will try to customize server URL, app name. First, we create two targets for 2 environments by duplicating the main target: For each target, we will define a custom macro. Here I ...

C++ #include "opencv2/objdetect/objdetect.hpp" #include "opencv2/highgui/highgui.hpp" #include "opencv2/imgproc/imgproc.hpp" #include <iostream> #include <stdio.h> using namespace std; using namespace cv; // Function Headers void detectAndDisp...

To set the environment to Development SET ASPNETCORE_ENVIRONMENT=Development Now running an Asp.Net Core application will be in the defined environment. Note There should be no space before and after the equality sign =. The command prompt should not be closed before running the application b...

If a target matches multiple pattern rules, make will use the one whose prerequisites exist or can be built. For example: %.o: %.c $(CC) $(CFLAGS) -c $< -o $@ %.o: %.s $(AS) $(ASFLAGS) $< -o $@ Will compile foo.c to foo.o or assemble foo.s to foo.o, depending on which one of foo...

Pattern rules can have multiple targets but, unlike normal rules, the recipe is responsible for making all the targets. For example: debug/%.o release/%.o: %.c $(CC) $(CFLAGS_DEBUG) -c $< -o debug/$*.o $(CC) $(CFLAGS_RELEASE) -c $< -o release/$*.o Is a valid rule, which will buil...

Passing a 2d array to a functions seems simple and obvious and we happily write: #include <stdio.h> #include <stdlib.h> #define ROWS 3 #define COLS 2 void fun1(int **, int, int); int main() { int array_2D[ROWS][COLS] = { {1, 2}, {3, 4}, {5, 6} }; int n = ROWS; int m...

In Java, any object or primitive type can be an array. Array indicies are accessed via arrayName[index], e.g. myArray[0]. Values in an array are set via myArray[0] = value, e.g. if myArray is an array of type String[] myArray[0] = "test"; public class CreateBasicArray{ public static ...