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Let's learn how to join strings together using concatenation.
- Our printed question is running up against the space where the user types their answer.
- We need to add a space onto the end of the user
question. - We can do this by taking the
questionstring, and concatenating, or joining, a string consisting of a single space onto the end of it.
// We can concatenate strings.
Console.WriteLine("a" + "b");
Console.WriteLine("some words" + "more words");
// If we want a space between the joined strings, we need
// to add it ourselves.
Console.WriteLine("some words" + " " + "more words");
// We can concatenate strings stored in variables.
string myString = "a string";
Console.WriteLine(myString + " abc");
// Notice that simply concatenating onto a string stored
// in a variable doesn't change the value in the variable.
Console.WriteLine(myString);
// To update the variable, we need to assign the concatenated
// value back to it.
myString += " abc";
Console.WriteLine(myString);
myString += " def";
Console.WriteLine(myString);
- Using string concatenation to fix our
askmethod:
static string Ask(string question)
{
Console.Write(question + " ");
return Console.ReadLine();
}
- Let's print what the user entered so they can confirm it's correct.
static void Main()
{
Console.WriteLine("Welcome to the cat food store!");
string entry = Ask("How many cans are you ordering?");
Console.WriteLine("You entered" + entry + "cans");
}
You entered11cans
- Oops! We need to add spaces surrounding
answer, so fix that:
static void Main()
{
Console.WriteLine("Welcome to the cat food store!");
string entry = Ask("How many cans are you ordering?");
Console.WriteLine("You entered " + entry + " cans");
}
You entered 11 cans
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In our cat food store program, our printed
question is running up against the space
0:00
where the user types their answer.
0:05
To fix this, we need to add a space
on to the end of the user question.
0:07
We can do this by taking the question
string and concatenating or
0:11
joining a string consisting of
a single space on to the end of it.
0:15
To concatenate two strings,
you just type a plus sign between them.
0:25
So this code here we'll join
the strings A and B together and
0:31
this would join the string some words and
more words together.
0:34
Let me save this and run it.
0:37
And here's the result.
0:44
You can see that the string some words
is smashed together with more words.
0:46
If we want a space between
the joint strings,
0:52
we'll need to add it ourselves by
a concatenating a third string in there.
0:54
Let me save this and re-run it.
0:59
There we go, and now there's a space.
1:04
We can also concatenate
strings stored in variables.
1:10
So let's declare a new variable named
myString and storeString in it.
1:13
And now, let's concatenate that
together with another string.
1:18
Let me save that.
1:23
And let's try running it,
there's the string from our variable,
1:27
and here's the string we
concatenated onto it.
1:32
One important thing to note, though,
is that simply concatenating onto
1:42
a string stored in a variable doesn't
change the value in the variable.
1:45
So, if we were trying to print
the content of my string again,
1:49
let's try that real quick.
1:52
You can see that my string still just
contains the value we originally assigned
1:56
to it, a string.
2:00
There's no abc on the end.
2:01
To update the value in the variable,
2:08
we need to assign the concatenated
value back to it.
2:09
We can do that with the += operator.
2:13
This will concatenate a new string
onto the string currently contained
2:15
in the myString variable.
2:20
And then assign that new
concatenated value back to myString.
2:22
So let's try printing that updated value,
save this and try running it.
2:26
And now you can see that myString
contains the updated value, a string abc.
2:34
I can even concatenate additional
strings onto the updated strings.
2:41
So let's add def and
2:45
assign that back to myString and
then print the resulting value.
2:47
And let's try running this,
and you can see that, first,
2:55
we updated myString so
that it contained a string abc, and
2:59
then we concatenated an additional
string onto that, a string abc def.
3:02
This is what the myString variable
contains at the end of the program.
3:08
So by assigning concatenated
strings back to the same variable,
3:13
you can keep building up longer and
longer strings.
3:16
Let's use string concatenation
to fix our ask method.
3:18
We'll simply take the value that we're
passing to the write method, and
3:23
concatenate a space onto the end of it.
3:28
That will cause there to be a space
between the question that gets asked and
3:31
the answer the user types.
3:35
So make sure to save that,
and let's try running it.
3:41
How many cans are you ordering?
3:45
Let's say 55, and
there's a space there now.
3:47
Right now, we're simply printing
the value the user enters so
3:52
we can debug it, but it would be helpful
for the user to know what they entered, so
3:54
let's make this a little more user
friendly and convert this into a sentence.
3:59
We'll do that using string
concatenation again.
4:04
We'll say you entered, As a string,
4:06
and then concatenate that together
with the value in the entry variable.
4:12
And concatenate that with
cans to end the sentence.
4:15
Save that let's try running it.
4:21
And whoops it joins the value we entered
together with the rest of the sentence but
4:27
theres no spaces surrounding
the value we entered.
4:32
So let's fix that.
4:36
We simply need to add spaces onto the end
of the string we're adding before
4:38
the entry and onto the start of
the string we're adding after the entry.
4:44
Let's save that.
4:49
And try running it again.
4:52
Okay, that looks much better.
4:56
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