What does "str" + x + "str" mean?

Question

Why would you use "str" + x + "str" in ImageLocation.

 private void CreateEnemies()
    {
        Random rnd = new Random();
        int x = rnd.Next(1, kindOfEnemies + 1);
        PictureBox enemy = new PictureBox();
        int loc = rnd.Next(0, panel1.Height - enemy.Height);
        enemy.SizeMode = PictureBoxSizeMode.StretchImage;
        enemy.ImageLocation = "Aliens/" + x + ".png";

    }

I don't understand why you would use this.

It inserts a (random) number x into the path, so it effectively loads a random image.. — TaW, Jul 24 '17 at 16:53
You don't understand the syntax or the motivation behind using a random number to build an image path? — Claudio Redi, Jul 24 '17 at 16:54
@Md Rakibul Islam If one of the answers solved your problem, please mark it as resolved to close this thread. If not please clarify what is still missing. — Iqon, Jul 25 '17 at 06:15

Iqon · Accepted Answer · 2018-11-19T10:49:31.617

The + operator is used for adding. If used on a string it will not add two strings, but concatenate them:

var text = "Hello" + "World" + "String";
Console.WriteLine(text); // Prints "HelloWorldString"

So the code above just constructs a string. Because the variable x is not of type int, .Net will automatically call .ToString().

int x = 5;
var text1 = "Aliens/" + x +".png"; // is the same as below.
var text2 = "Aliens/" + x.ToString() +".png"; // is the same as above.

Console.WriteLine(text); // Prints "Aliens/5.png"

In C# version 6 and above you can also use string interpolation, which makes things clearer:

var text1 = $"Aliens/{x}.png"; // is the same as below.
var text2 = $"Aliens/{x.ToString()}.png"; // is the same as above.

With string interpolation, you can embed variables into a string, by placing them into curly braces.

Note that the string has to start with a $.

score 0 · Answer 2 · answered Jul 24 '17 at 16:54

0

+ is used for string concatenation

answered Jul 24 '17 at 16:54

wdc

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Wyatt Shuler · Answer 3 · 2017-07-24T16:56:21.423

0

It is concatenating strings together. So "Aliens/" + The string value of 'x' + ".png" are being 'added' together.

Lets say:

int x = 1

The output string would be

"Aliens/1.png"

edited Jul 24 '17 at 16:56

answered Jul 24 '17 at 16:55

Wyatt Shuler

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score 0 · Answer 4 · answered Jul 24 '17 at 16:55

This is a way to randomize the image of the alien that you get.

Your solution has a folder called Aliens with files named 0.png, 1.png, 2.png, and so on in it. Each file has an image of an "alien", which your program loads into a PictureBox. Your code picks one of these files at random, using string concatenation.

With C# 6 and newer you can use string interpolation:

enemy.ImageLocation = $"Aliens/{x}.png";

What does "str" + x + "str" mean?

4 Answers4