Don't understand why this std::cout is printing this

Question

I got is c++ code below.

#include <iostream>
using namespace std;
int main()
{
char ch;
int ct1, ct2;
ct1 = ct2 = 0;
while ((ch = cin.get()) != '$')
{
    cout << ch;
    ct1++;
    if (ch = '$')
        ct2++;
    cout << ch;
}
cout << "ct1 = " << ct1 << ", ct2 = " << ct2 << "\n";
system("pause");
return 0;
}

Now you can tell what gonna happen if input.

  hi$<ENTER>

and the the output should be this right.

hi ct1 = 2, ct2 = 0

But the real output is this.

h$i$ct1 = 2, ct2 = 2.

why is it outputting that i don't understand and how should i fix it.

and i'm using Visual Studio Express 2013 preview for windows desktop.

You have `if (ch = '$')`. That's an assignment, not a comparison, so it counts as `true` in every iteration of the loop. You want `if (ch == '$')` instead. — jogojapan, Jul 12 '13 at 11:19
This question is about a typo (or something similar). Voting to put on hold. — jogojapan, Jul 12 '13 at 11:22
`ch` should have type `int` (or you should write `while ( cin.get() && ch != '$' )`; as written, you'll go into an endless loop if you reach end of file. — James Kanze, Jul 12 '13 at 11:23
Also, if you really mean `if ( ch == '$' )` in the loop, the condition will always be false (since you don't enter the loop if `ch == '$'). — James Kanze, Jul 12 '13 at 11:25
I just realized my comment is a bit misleading. The assignment of course does not necessarily evaluate to `true`. It evaluates to whatever is assigned, which is `$`, and that evaluates to `true` because it is not zero. — jogojapan, Jul 12 '13 at 11:27

score 2 · Answer 1 · answered Jul 12 '13 at 11:42

2

first, there is a problem in this code, if(ch = '$'), second, I think the real output is "hhct1 = 1,ct2 = 0", because when the char is equal to '$', can get into the loop.

answered Jul 12 '13 at 11:42

liuan

299
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Matthieu Harlé · Accepted Answer · 2013-07-12T11:30:49.437

0

In your if statement, you actually assigned $ to ch : if(ch = '$'). This should be :

if(ch == '$')

Also, your real output will be like this : hhiict1 = 2, ct2 = 0, since you wrote cout << ch; two times in your while statement.

edited Jul 12 '13 at 11:30

answered Jul 12 '13 at 11:21

Matthieu Harlé

739
1
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32

score 0 · Answer 3 · answered Jul 12 '13 at 11:22

0

You are using assignment operator = instead of == in if condition. I would recommend.

if('$' == ch)

answered Jul 12 '13 at 11:22

praks411

1,972
16
23

score 0 · Answer 4 · answered Jul 12 '13 at 11:22

0

while ((ch = cin.get()) != '$')
{
    cout << ch;
    ct1++;
    if (ch = '$') // << here is the heck
          ^^^     // did you mean == ?
        ct2++;
    cout << ch;
}

answered Jul 12 '13 at 11:22

4pie0

29,204
9
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118

Don't understand why this std::cout is printing this

4 Answers4