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24.9
And if that's the case, I'm going to arbitrarily return 1.
439.65
2.48
So recall that main can return values.
442.13
2.12
0 means all is well.
444.25
1.2
1 or any other non-zero value means something is wrong.
445.45
2.6
So maybe that's what I was doing wrong earlier, just not error checking.
448.05
3
So let's try that.
451.05
1.04
Now, let me declare a variable of type string called t and assign it to s.
452.09
5.94
So in other words, I want to copy s into t.
458.03
3.09
And I know that this happens from the right to the left.
461.12
2.35
So that's as I think it should be.
463.47
2.41
And then, if strleng of t is greater than 0--
465.88
7.302
you know what, I'm going to do one other thing.
473.182
1.958
Not just copy it.
475.14
0.924
I'm going to go ahead and do this.
476.064
1.416
Recall, that you can treat strings as arrays.
477.48
2.02
So I'm going to say the zeroth character, the first character of t--
479.5
3.477
you know what?
482.977
0.583
I want to uppercase it.
483.56
1.61
I want to really make sure that these two strings are indeed
485.17
2.79
different as I intend.
487.96
1.58
And let's go ahead now and do this.
489.54
3.3
Let me go ahead now and do printf of s.
492.84
4.5
And let me plug-in s's value in a new line.
497.34
2.18
Plug-in s.
499.52
0.7
And then printf t:%s for a placeholder again.
500.22
4.87
Comma t semi-colon.
505.09
1.74
So in other words, if the length of t is greater than zero,
506.83
3.69
let's capitalize it by changing that first character.
510.52
2.764
And then, just print out s and t.
513.284
1.375
And surely, by capitalizing only t, I should see only one capitalized word.
514.659
5.091
Now, I'm using both strleng and two upper.
519.75
1.812
So rather than let Clang have a chance to yell at me, I'm going to go in here
521.562
3.208
and preemptively add ctype.h.
524.77
3.056
Which recall is a library you might have seen
527.826
1.874
or certainly will soon see that has a number of functions in it.
529.7
3.34
Among them, two upper.
533.04
1.18
And then, I also need to include string.h, so that I can use strlen--
534.22
4.094
the function that gives me the length of the string.
538.314
2.166
So Clang would have yelled at me if I forgot that, but let me preemptively
540.48
2.89
solve that problem.
543.37
0.82
And now, do make copies zero.
544.19
2.35
All seems to be well.
546.54
1.03
Let's run dot slash copy 0.
547.57
1.861
All right.
549.431
0.499
Let's go ahead and type in-- how about just my own name in all lowercase.
549.93
6.05
Huh?
555.98
1.31
Now, why is this confusing?
557.29
2.04
So I wrote code that got a string from the user and stored it in s.
559.33
5.53
I then wrote code that declared a second variable, t.
564.86
3.48
And I set t equal to s, thereby making I would
568.34
2.88
think a copy-- as in past weeks of using the assignment operator.
571.22
3.7
Then down here, I made sure t was long enough.
574.92
2.21
That's just a quick sanity check.
577.13
1.71
And then on this line here, I'm just saying,
578.84
3.18
set the first character of t, t bracket 0, equal to the result of upper casing
582.02
5.85
the first character of t.
587.87
2.13
So the only code that's touching t is this one here.
590
3.37
And yet, somehow my name gets capitalized both in s and in t.
593.37
5.38
So what is it that's actually going on here?
598.75
3.67
It seems to be broken still.
602.42
2.559
In fact, let me go ahead and open another example, rather than type
604.979
2.791
this one out ourselves.
607.77
1.73
Let me go ahead and open up an example called no swap.
609.5
4.42
As the name suggests, it's a bit of a spoiler.
613.92
2.59
I wrote this program in advance to do the following.
616.51
2.82
First, I've included standard io.h, so I can use printf.
619.33
3.61
I have a prototype of my function called swap up here, because indeed,
622.94
3.55
the goal at hand I decided was I just want to write a simple function that
626.49
4.11
swaps two values.
630.6
1.69
Given a and b, make b a and a, b.
632.29
2.86
And then, return.
635.15
0.99
So I'm just going to arbitrarily test this out by declaring a variable x.
636.14
3.06
Setting it equal to 1.
639.2
1.17
A variable y setting it equal to 2.
640.37
2.35
And then, just as a sanity check, I'm going to print out x is such and such,
642.72
3.3
y is such and such.
646.02
1.18
And then, I'm going to claim swapping dot dot dot.
647.2
2.92
And then, the key line is apparently this one.
650.12
2.68
Call a function called swap, passing in x and y.
652.8
3.51
And if I implemented swap correctly, this should swap the two variables.
656.31
4.09
Thereafter, I'm going to claim swapped x as such and such, y as such and such.
660.4
4.69
So let's run this program and see what else is apparently a lie.
665.09
5.19
Make no swap in my source directory.
670.28
6.62
./noswap enter.
676.9
3.71
And if we scroll back up in my history, you'll see x is 1, y is 2.
680.61
4.95
Swapping swapped.
685.56
1.66
x is 1, y is 2.
687.22
1.431
All right.
688.651
0.499
So maybe just the swap function is buggy.
689.15
1.96
This isn't necessarily indicative of a misunderstanding.
691.11
3.17
So let's look at the implementation of swap.
694.28
2.01
Swap returns no value and I think that's OK, so long as it takes inputs.
696.29
4.5
Swap takes two inputs, an ints and an ints, called a and b respectively.
700.79
4.64
And then, let's consider how this works.
705.43
1.72
So I've declared a temporary variable, called temp--
707.15
3.225
though I could call it anything I want.
710.375
1.625
And I'm storing in it the value a.
712
2.28
So I'm taking a-- and it's the number 1.
714.28
1.975
And I'm just temporarily storing the number 1
716.255
1.875
in this additional temporary variable, so that I now
718.13
2.22