Tutorial by Examples: c

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. ...

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 ...

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...

For lambdas with a single return statement, or multiple return statements whose expressions are of the same type, the compiler can deduce the return type: // Returns bool, because "value > 10" is a comparison which yields a Boolean result auto l = [](int value) { return value &gt...

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...

To encode a string into a byte array, you can simply use the String#getBytes() method, with one of the standard character sets available on any Java runtime: byte[] bytes = "test".getBytes(StandardCharsets.UTF_8); and to decode: String testString = new String(bytes, StandardCharsets.U...

Tuples can be decomposed into individual variables with the following syntax: let myTuple = (name: "Some Name", age: 26) let (first, second) = myTuple print(first) // "Some Name" print(second) // 26 This syntax can be used regardless of if the tuple has unnamed properti...

Functions can return tuples: func tupleReturner() -> (Int, String) { return (3, "Hello") } let myTuple = tupleReturner() print(myTuple.0) // 3 print(myTuple.1) // "Hello" If you assign parameter names, they can be used from the return value: func tupleReturner(...

Occasionally you will find the need to encode binary data as a base64-encoded string. For this we can use the DatatypeConverter class from the javax.xml.bind package: import javax.xml.bind.DatatypeConverter; import java.util.Arrays; // arbitrary binary data specified as a byte array byte[] bi...

First, establish if the device is capable of accepting Touch ID input. if (context.CanEvaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, out AuthError)) If it does then we can display the Touch ID UI by using: context.EvaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometri...

Here is an example of a Bosun config file used in a development environment: tsdbHost = localhost:4242 httpListen = :8070 smtpHost = localhost:25 emailFrom = [email protected] timeAndDate = 202,75,179,136 ledisDir = ../ledis_data checkFrequency = 5m notification example.notification { ...

The quick start guide includes information about using Docker to stand up a Bosun instance. $ docker run -d -p 4242:4242 -p 80:8070 stackexchange/bosun This will create a new instance of Bosun which you can access by opening a browser to http://docker-server-ip. The docker image includes HBase/O...

With Stream Controller add-on enabled, you can use Channel Groups to subscribe to a 1000's of channels from a single client. You do this by creating a channel group and adding channels to the channel group. We'll assume pubnub variable has been initialized properly with your keys. Create a generic ...

Preferences objects always represent a specific node in a whole Preferences tree, kind of like this: /userRoot ├── com │   └── mycompany │   └── myapp │   ├── darkApplicationMode=true │   ├── showExitConfirmation=false │   └── windowMaximized=true └── org └...