This is either a bug in TypeScript or a concious design decision, but you can work around it using:

    var myBool: bool = true;
    var myString: string = String(myBool);
    alert(myString);

In JavaScript booleans override the `toString` method, which is available on any `Object` (pretty much everything in JavaScript inherits from `Object`), so...

    var myString: string = myBool.toString();

... should probably be valid.

There is also another work around for this, but I personally find it a bit nasty:

    var myBool: bool = true;
    var myString: string = &lt;string&gt;&lt;any&gt; myBool;
    alert(myString);

For those looking for an alternative, another way to go about this is to use a [template literal][1] like the following:

    const booleanVal = true;
    const stringBoolean = `${booleanVal}`;

The real strength in this comes if you don&#39;t know for sure that you are getting a boolean value. Although in this question we know it is a boolean, thats not always the case, even in TypeScript(if not fully taken advantage of).


  [1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals

One approach is to use the Ternary operator:

    myString = myBool? &quot;true&quot;:&quot;false&quot;;

This if you have to handle null values too:

    stringVar = boolVar===null? &quot;null&quot; : (boolVar?&quot;true&quot;:&quot;false&quot;);

```
return Boolean(b) ? &#39;true&#39;:&#39;false&#39;
```

For MySQL Data type of &quot;enum&quot; and &quot;set&quot; what are the differences and advantages and disadvantages of using one versus the other?

Example data type:

- enum(&#39;A&#39;, &#39;B&#39;, &#39;C&#39;)
- set(&#39;A&#39;, &#39;B&#39;, &#39;C&#39;)

The only difference that I am aware of is that ENUM only allows one value to be selected versus SET allows multiple values to be selected.

MySQL enum vs. set

When reading a long file by vi editor, it would be very nice to get back to the beginning of the file by some short cuts when you really need to do so. Even &lt;kbd&gt;ctrl&lt;/kbd&gt;+&lt;kbd&gt;B&lt;/kbd&gt; sometimes is too slow. Does anyone know such a tool?

Is there a short cut for going back to the beginning of a file by vi editor?

I have a really simple issue, I can&#39;t get to **convert a simple boolean to a string value** in TypeScript.

I have been roaming through documentation and I could not find anything helpful. Of course I tried to use the `toString()` method but it does not seem to be implemented on bool.

----------
Edit: I have almost no JavaScript knowledge and came to TypeScript with a C#/Java background.

TypeScript: Convert a bool to string value

I have a really simple issue, I can't get to convert a simple boolean to a string value in TypeScript.
I have been roaming through documentation and I could not find anything helpful. Of course I tried to use the <code>toString()</code> method but it does not seem to be implemented on bool.
<hr>
Edit: I have almost no JavaScript knowledge and came to TypeScript with a C#/Java background.

I generally prefer to code R so that I don&#39;t get warnings, but I don&#39;t know how to avoid getting a warning when using `as.numeric` to convert a character vector.

For example:

    x &lt;- as.numeric(c(&quot;1&quot;, &quot;2&quot;, &quot;X&quot;))

Will give me a warning because it introduced NAs by coercion.  I want NAs introduced by coercion - is there a way to tell it &quot;yes this is what I want to do&quot;.  Or should I just live with the warning?

Or should I be using a different function for this task?

How to avoid warning when introducing NAs by coercion

I have below query and need to cast `id` to `varchar`

**Schema**

    create table t9 (id int, name varchar (55));
    insert into t9( id, name)values(2, &#39;bob&#39;);

**What I tried**

    select CAST(id as VARCHAR(50)) as col1 from t9;

    select CONVERT(VARCHAR(50),id) as colI1 from t9;

but they don&#39;t work. Please suggest.

Cast int to varchar

I have a function that casts a `double` on `string` values. 

    string variable = &quot;5.00&quot;; 

    double varDouble = (double)variable;
 
A code change was checked in and the project builds with the error: `System.InvalidCastException: Specified cast is not valid.` 

However, after doing the following...

    string variable = &quot;5.00&quot;; 

    double varDouble = Convert.ToDouble(variable);

...the project builds without any errors.

**What is the difference between casting and using the `Convert.To()` method?** Why does casting throw an `Exception` and using the `Convert.To()` does not?

Difference between casting and using the Convert.To() method

I&#39;m trying to cast the output of a value to an integer:

    @Value(&quot;${api.orders.pingFrequency}&quot;)
    private Integer pingFrequency;

The above throws the error 

    org.springframework.beans.TypeMismatchException: 
        Failed to convert value of type &#39;java.lang.String&#39; to required type &#39;java.lang.Integer&#39;; 
    nested exception is java.lang.NumberFormatException: 
        For input string: &quot;(java.lang.Integer)${api.orders.pingFrequency}&quot;

I&#39;ve also tried `@Value(&quot;(java.lang.Integer)${api.orders.pingFrequency}&quot;)`

Google doesn&#39;t appear to say much on the subject.  I&#39;d like to always be dealing with an integer instead of having to parse this value everywhere it&#39;s used.

**Workaround**

I realize a workaround may be to use a setter method to run the conversion for me, but if Spring can do it I&#39;d rather learn something about Spring.

@Value annotation type casting to Integer from String

I&#39;ve got an application that stores some data in DynamoDB using Jackson to marshall my complex object into a JSON. 

For example the object I&#39;m marshalling might look like this:

    private String aString;
    private List&lt;SomeObject&gt; someObjectList;

Where SomeObject might look like this:

    private int anInteger;
    private SomeOtherObject;

and SomeOtherObject might look like this:

    private long aLong;
    private float aFloat; 

This is fine an the object gets marshalled no problem and stored in the DB as a JSON string.

When it comes time to retrieve the data from DynamoDB Jackson automatically retrieves the JSON and converts it back... EXCEPT that &#39;someObjectList&#39; is returned as a `List&lt;LinkedHashMap&gt;` not as a `List&lt;SomeObject&gt;`! This is standard behaviour for Jackson, its not a mistake that this is happening.

So now this leads to a problem. My code base thinks its dealing with a `List&lt;SomeObject&gt;` but the reality is that its handling a `List&lt;LinkedHashMap&gt;`! My question is how do I get my LinkedHashMap back into a &#39;SomeObject&#39;. Obviously this is a manual process but what I mean is I can&#39;t even extract the values.

If I do this:

    for (LinkedHashMap lhm : someObjectList) {
        // Convert the values back
    }

I get a compile error telling me that someObjectList is of type &#39;SomeObject&#39; not LinkedHashMap.

If I do this:

    for (SomeObject lhm : someObjectList) {
        // Convert the values back
    }

I get a runtime error telling me that LinkedHashMap cannot be cast to &#39;SomeObject&#39;.


Casting LinkedHashMap to Complex Object

The statement gives me the date and time. 

How could I modify the statement so that it returns only the date (and not the time)?

    SELECT to_timestamp( TRUNC( CAST( epoch_ms AS bigint ) / 1000 ) );

PostgreSQL: how to convert from Unix epoch to date?

How can I convert  `Map&lt;String,Object&gt;` to `Map&lt;String,String&gt;` ?

This does not work:

    Map&lt;String,Object&gt; map = new HashMap&lt;String,Object&gt;(); //Object is containing String
    Map&lt;String,String&gt; newMap =new HashMap&lt;String,String&gt;(map);



Convert Map&lt;String,Object&gt; to Map&lt;String,String&gt;

I have a named character vector returned from xmlAttrs like this:

    testVect &lt;- structure(c(&quot;11.2.0.3.0&quot;, &quot;12.89&quot;, &quot;12.71&quot;), .Names = c(&quot;db_version&quot;, 
                 &quot;elapsed_time&quot;, &quot;cpu_time&quot;))

I would like to convert it to a data frame that looks like this:

    testDF &lt;- data.frame(&quot;db_version&quot;=&quot;11.2.0.3.0&quot;,&quot;elapsed_time&quot;=12.89,&quot;cpu_time&quot;=12.71)
    head(testDF)
      db_version elapsed_time cpu_time
    1 11.2.0.3.0        12.89    12.71


Convert Named Character Vector to data.frame

I have a function which receives a `[]byte` but what I have is an `int`, what is the best way to go about this conversion ?

    err = a.Write([]byte(myInt))

I guess I could go the long way and get it into a string and put that into bytes, but it sounds ugly and I guess there are better ways to do it.

Convert an integer to a byte array

I have a data frame with alpha-numeric keys which I want to save as a csv and read back later. For various reasons I need to explicitly read this key column as a string format, I have keys which are strictly numeric or even worse, things like: 1234E5 which Pandas interprets as a float. This obviously makes the key completely useless.

The problem is when I specify a string dtype for the data frame or any column of it I just get garbage back. I have some example code here:

    df = pd.DataFrame(np.random.rand(2,2),
                      index=[&#39;1A&#39;, &#39;1B&#39;],
                      columns=[&#39;A&#39;, &#39;B&#39;])
    df.to_csv(savefile)

The data frame looks like:

               A         B
    1A  0.209059  0.275554
    1B  0.742666  0.721165

Then I read it like so:

    df_read = pd.read_csv(savefile, dtype=str, index_col=0)

and the result is:

       A  B
    B  (  &lt;
           

Is this a problem with my computer, or something I&#39;m doing wrong here, or just a bug?

Pandas reading csv as string type

Why doesn&#39;t Typescript warn me that the function I am defining does not match the interface declaration, but it does warn me if I try to invoke the function.

    interface IFormatter {
        (data: string, toUpper : boolean): string;
    };

    //Compiler does not flag error here.
    var upperCaseFormatter: IFormatter = function (data: string) {
        return data.toUpperCase();
    }  

    upperCaseFormatter(&quot;test&quot;); //but does flag an error here.



Typescript Function Interface

This works in Javascript

    new Date() - new Date(&quot;2013-02-20T12:01:04.753Z&quot;)

But in typescript I can&#39;t rest two new Dates

    Date(&quot;2013-02-20T12:01:04.753Z&quot;)

Don&#39;t work because paremater not match date signature

How can I calculate the time between 2 Dates in typescript

Does Typescript currently (or are there plans to) support the [safe navigation][1] operator of `?.`

ie:

    var thing = foo?.bar
    // same as:
    var thing = (foo) ? foo.bar : null;

Also, is there a more common name for this operator (it&#39;s incedibly hard to google for).


  [1]: http://mrhaki.blogspot.com.au/2009/08/groovy-goodness-safe-navigation-to.html

Does Typescript support the ?. operator? (And, what&#39;s it called?)

I have an array that I&#39;ve created in TypeScript and it has a property that I use as a key. If I have that key, how can I remove an item from it?

How do I remove an array item in TypeScript?

I meant to write a parameter of type `number`, but I misspelled the type, writing `Number` instead. 

On my IDE (JetBrains WebStorm) the type `Number` is written with the same color that is used for the primitive type `number`, while if I write a name of a class (known or unknown) it uses a different color, so I guess that somehow it recognizes the misspelled type as a correct/almost-correct/sort-of-correct type.
 
When I compile the code, instead of complaining for example that the compiler couldn&#39;t found a class named `Number`, TSC writes this error message: 

    Illegal property access

Does that mean that `number` and `Number` both co-exists as different types?

If this is true, which is the difference between those classes?

If this is not the case, then why it simply didn&#39;t write the same error message it displays for unknown classes (&quot;The name &#39;Number&#39; does not exist in the current scope&quot;)

This is the code:


    class Test
    {
        private myArray:string[] = [&quot;Jack&quot;, &quot;Jill&quot;, &quot;John&quot;, &quot;Joe&quot;, &quot;Jeff&quot;];

        // THIS WORKS
        public getValue(index:number):string
        {
            return this.myArray[index];
        }

        // THIS DOESN&#39;T WORK: ILLEGAL PROPERTY ACCESS
        public getAnotherValue(index:Number):string
        {
            return this.myArray[index]; 
        }
    }




Content Type	Original Author	Original Content on Stackoverflow
Question	Ucodia	View Question on Stackoverflow
Solution 1 - Casting	Fenton	View Answer on Stackoverflow
Solution 2 - Casting	Jon Black	View Answer on Stackoverflow
Solution 3 - Casting	Tolga	View Answer on Stackoverflow
Solution 4 - Casting	Luca C.	View Answer on Stackoverflow
Solution 5 - Casting	priya veruva55	View Answer on Stackoverflow

TypeScript: Convert a bool to string value

Casting Problem Overview

Casting Solutions

Solution 1 - Casting

Solution 2 - Casting

Solution 3 - Casting

Solution 4 - Casting

Solution 5 - Casting

Is there a short cut for going back to the beginning of a file by vi editor?

MySQL enum vs. set

Attributions