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The operators << and >> are commonly used as "write" and "read" operators: std::ostream overloads << to write variables to the underlying stream (example: std::cout) std::istream overloads >> to read from the underlying stream to a variable (example: s...

Using the following code with the format string yyyy/MM/dd hh:mm.ss, we will receive the following output 2016/04/19 11:45.36 // define the format to use String formatString = "yyyy/MM/dd hh:mm.ss"; // get a current date object Date date = Calendar.getInstance().getTime(); //...

Sourcing a file is different from execution, in that all commands are evaluated within the context of the current bash session - this means that any variables, function, or aliases defined will persist throughout your session. Create the file you wish to source sourceme.sh #!/bin/bash export A=...

Bosun alerts are defined in the config file using a custom DSL. They use functions to evaluate time series data and will generate alerts when the warn or crit expressions are non-zero. Alerts use templates to include additional information in the notifications, which are usually an email message and...

This method can be used to convert a formatted string representation of a date into a Date object. /** * Parses the date using the given format. * * @param formattedDate the formatted date string * @param dateFormat the date format which was used to create the string. ...

The base keyword is used to access members from a base class. It is commonly used to call base implementations of virtual methods, or to specify which base constructor should be called. Choosing a constructor public class Child : SomeBaseClass { public Child() : base("some string for th...

An assertion is a statement used to assert that a fact must be true when that line of code is reached. Assertions are useful for ensuring that expected conditions are met. When the condition passed to an assertion is true, there is no action. The behavior on false conditions depends on compiler fl...

C11 Static assertions are used to check if a condition is true when the code is compiled. If it isn't, the compiler is required to issue an error message and stop the compiling process. A static assertion is one that is checked at compile time, not run time. The condition must be a constant expres...

To find files/directories with a specific name, relative to pwd: $ find . -name "myFile.txt" ./myFile.txt To find files/directories with a specific extension, use a wildcard: $ find . -name "*.txt" ./myFile.txt ./myFile2.txt To find files/directories matching one of ma...

Sometimes we will need to run commands against a lot of files. This can be done using xargs. find . -type d -print | xargs -r chmod 770 The above command will recursively find all directories (-type d) relative to . (which is your current working directory), and execute chmod 770 on them. The -...

lscount returns a time bucketed count of matching documents in the LogStash index, according to the specified filter. A trivial use of this would be to check how many documents in total have been received in the 5 minutes, and alert if it is below a certain threshold. A Bosun alert for this might ...

lsstat returns various summary stats per bucket for the specified field. The field must be numeric in elastic. rStat can be one of avg, min, max, sum, sum_of_squares, variance, std_deviation. The rest of the fields behave the same as lscount, except that there is no division based on bucketDuratio...

The Promise.resolve static method can be used to wrap values into promises. let resolved = Promise.resolve(2); resolved.then(value => { // immediately invoked // value === 2 }); If value is already a promise, Promise.resolve simply recasts it. let one = new Promise(resolve => ...

At its simplest, a unit test consists of three stages: Prepare the environment for the test Execute the code to be tested Validate the expected behaviour matches the observed behaviour These three stages are often called 'Arrange-Act-Assert', or 'Given-When-Then'. Below is example in C# tha...

#include <stdio.h> #define is_const_int(x) _Generic((&x), \ const int *: "a const int", \ int *: "a non-const int", \ default: "of other type") int main(void) { const int i = 1; int j = 1; double...

#include <stdio.h> void print_int(int x) { printf("int: %d\n", x); } void print_dbl(double x) { printf("double: %g\n", x); } void print_default() { puts("unknown argument"); } #define print(X) _Generic((X), \ int: print_int, \ double: pri...

A lambda expression provides a concise way to create simple function objects. A lambda expression is a prvalue whose result object is called closure object, which behaves like a function object. The name 'lambda expression' originates from lambda calculus, which is a mathematical formalism invented...

If you specify the variable's name in the capture list, the lambda will capture it by value. This means that the generated closure type for the lambda stores a copy of the variable. This also requires that the variable's type be copy-constructible: int a = 0; [a]() { return a; // Ok, 'a' ...

On an ext filesystem, each file has a stored Access, Modification, and (Status) Change time associated with it - to view this information you can use stat myFile.txt; using flags within find, we can search for files that were modified within a certain time range. To find files that have been modifi...

Tuples group multiple values into a single compound value. The values within a tuple can be of any type and do not have to be of the same type as each other. Tuples are created by grouping any amount of values: let tuple = ("one", 2, "three") // Values are read using index n...