C / C++ / MFC

Re: #include cpp file - how it works?

5-Mar-14 5:31

Without seeing all the code in the included file it is impossible to answer that.

leon de boer9-Mar-14 8:51

leon de boer

9-Mar-14 8:51

You are spot on Val you will get multiple inclusions if the file is multiple included, unless the file contains standard one time load #ifdef protection around the top and bottom

If the programmer knew what they were doing they would have something that looks like this top/bottom of include file

// PROTECTION TO STOP MULTIPLE UNIT LOADING
#ifndef _FILENAME_ID_
#define _FILENAME_ID_

#endif

It is still quite common in a very specific circumstance .. can you think what it might be Smile | :)

I will give you a hint:

I know the old version of windows.h from Microsoft did it but they changed it all a few years ago when they broke that unit up. You will probably also find it on the android source unless they worked there way around it.

CMap class questions [Solved]

econy5-Mar-14 2:14

5-Mar-14 2:14

I use a CmapStringToString object, put over 10000 key-value pairs into the object.

But I use:
test1 = mStrMap.GetCount();
test2 = mStrMap.GetHashTableSize();

try to get the map size.

test1 = 0x00000299
test2 = 0x00000011

I wonder what the meaning of GetCount(), and GetHashTableSize();

modified 5-Mar-14 11:12am.

CPallini5-Mar-14 2:47

CPallini

5-Mar-14 2:47

With the following code

C++

CMapStringToString mss;
//mss.InitHashTable(32767);


for (int i=0; i<10000; ++i)
{
    CString k,v;
    k.Format("%05d", i);
    v.Format("Foo%02d", i%100);
    mss[k] = v;
}
int count = mss.GetCount();
int hsize = mss.GetHashTableSize();

I get:
count = 10000
hsize = 17

I don't know what exactly GetHashTableSize returns, the documentation is not much detailed about.

Veni, vidi, vici.

econy5-Mar-14 3:18

5-Mar-14 3:18

My fault, checked again, GetCount() works well for me too.

Richard MacCutchan5-Mar-14 3:13

5-Mar-14 3:13

See http://msdn.microsoft.com/en-us/library/9ah6bd2h.aspx[^] for details about the hash table size. Are you certain you added 1000 items?

econy5-Mar-14 3:44

5-Mar-14 3:44

Sorry, my fault, checked again, GetCount() return value is right.
but don't know what is the meaning of GetHashTableSize();

Richard MacCutchan5-Mar-14 4:37

5-Mar-14 4:37

That's why I gave you a link to the MSDN page that explains it.

econy5-Mar-14 4:07

5-Mar-14 4:07

Determines the number of elements in the hash table for the map. // msdn: GetHashTableSize();
Retrieves the number of elements in the map. //msdn: GetCount()

And I read some articles, they say Hashmap is equivalent to Hashtable.

So, what is the difference between GetCount() and GetHashSize() confused me

Richard MacCutchan5-Mar-14 4:39

if/else, expression can not be used as a function. C program

5-Mar-14 4:39

econy wrote:
So, what is the difference between GetCount() and GetHashSize()

GetCount returns the number of elements in the Map, e.g. 1000. GetHashSize gives the size of the Hash table that is used to manage the Map; in most cases this information is not useful to you.

cstudent14-Mar-14 20:37

Re: if/else, expression can not be used as a function. C program

4-Mar-14 20:37

Hi everyone, I am taking my first programming class and am at a loss on this program. Any tips for making this wrk? Thanks!

#include<stdio.h>
int main()

{
int month,day,opselect;

printf("\nEnter a month between 1 and 12: \n ");
scanf("%d",&month);

while (month < 1 || month > 12)
{
printf("Error the month entered is not valid.\n");
printf("\nEnter a month between between 1 and 12: ");
scanf("%d",&month);
}

printf("The month accepted is %d\n",month);
printf("\nEnter a day between 1 and 31: \n ");
scanf("%d",&day);
scanf("%d",opselect);

switch (opselect)

if (month=2)
(day < 1 || day > 28);

{
printf("Error the day entered is not valid.\n");
printf("\nEnter a day between 1 and 28\n");
scanf("%d,&day");
}

else (month=4,6,9,11)
(day < 1 || day > 30);

{
printf("Error the day entered is not valid.\n");
printf("\nEnter a day between 1 and 30\n");
scanf("%d,&day");
}
return 0;
}

errors are "else w/o a previous if"
and "expression can not be used as a function"

Jochen Arndt4-Mar-14 21:12

Jochen Arndt

4-Mar-14 21:12

You code contains many errors:

The scanf() call for opselect misses the ampersand &.
There is an empty switch statement.
C/C++ comparisons use two equal signs.
This is a complete if sequence:

C++

if (month=2)
    (day < 1 || day > 28);

Because there is other code following before the else, the compiler can not found any corresponding if and generates an error. The code following the if statement is an expression (day < 1 || day > 28). But the compiler expects a statement or a function call and generates another error.

As already noted, comparisons use two equal signs. Your code assings the value 2 to month and the if condition is always true.

I guess you want something like this:

C++

if (month == 2 && (day < 1 || day > 28))
{
// some code
}
else if ((month == 4 || month == 6 || month == 9 || month == 11) && (day < 1 || day > 30))
{
// some code
}

Re: if/else, expression can not be used as a function. C program

cstudent15-Mar-14 7:14

Re: if/else, expression can not be used as a function. C program

5-Mar-14 7:14

Thanks, I am trying to implement your suggestions here is what I currently have..

#include <stdio.h>
#define MAXCOUNT 10

int main ()
{
int opselect;
int day, month;

printf("Enter a month between 1-12 :");
scanf("%d", &month);
printf("Enter a number for the day of the month");
scanf("%d", &day);
scanf("%d", &opselect);

switch (opselect) {

case 1:
if (month==2 && (day < 1 || > 28))
{printf("\nEnter a day between 1 and 28: \n ");
scanf("%d",&day);
}

case 2:
else if (month==4 || month==6 || month==9 || month==11)&&(day < 1 || day > 30))
{printf("\nEnter a day between 1 and 30: \n ");
scanf("%d",&day);
}

case 3:
else if (month==3 || month==5 || month==7 || month==10 || month==12)&&(day < 1 || day > 31))
{printf("\nEnter a day between 1 and 31: \n ");
scanf("%d",&day);
}

printf("The day accepted is %d\n",day);

return 0;
}

I am getting a ton of errors here, expected primary-expression before else, expected; before else.

What I am trying to do is based on the month input prompt for a the proper number of days in the month(2=28, 1=31 etc)and get in error message if you enter the wrong days(29 in Feb for example)

Jochen Arndt5-Mar-14 7:40

Jochen Arndt

5-Mar-14 7:40

You are mixing a switch statement with if - else statements. That is not allowed. What is the opselect for? It seems unnecessary.

A more sophisticated solution would use an own function that checks if a day/month combination is valid:

C++

if (!CheckDate(month, day))
{
    printf("\nInvalid day/month combination. Please enter a valid day:\n");
    scanf("%d",&day);
}

Re: if/else, expression can not be used as a function. C program

cstudent15-Mar-14 7:58

Re: if/else, expression can not be used as a function. C program

5-Mar-14 7:58

This assignment calls for a switch statement, I thought you needed opselect when using a switch? I tired using case:1, case 2 etc..., but I couldn't make it work. How do I do the switch w/o the if statements? Thank you so much for your help.

cstudent15-Mar-14 8:03

Re: if/else, expression can not be used as a function. C program

5-Mar-14 8:03

Thank you!!! Removed opselect and it works!

Trace199524-Mar-14 15:16

Trace1995

24-Mar-14 15:16

I donot know your C program.
Please talk me you realize the function.

I come from China.My English is not good.I hope you can understand my replay.

Send global Touch event

cedricvictor4-Mar-14 18:42

cedricvictor

4-Mar-14 18:42

Dear all:

I get touch data by used HID.dll, it is raw data.
I wanna process the raw data, before send it to OS.

How can I send touch to OS, using postmessage or sendmessage?

if so, How can I use it?

Thank for your help, Victor.

Speed up a square root c++ prog

Craig McRae4-Mar-14 9:00

Craig McRae

4-Mar-14 9:00

Hello All, Could you help me speed up a program? It's designed to find the square root of a number.
<pre lang="c++">
#include<iostream>

using namespace std;

int main()
{
float a;
float c;
cout << "Square root calculator!" << endl;
cout << "Enter the number you want to square root" << endl;
cin >> a;
cout << "Enter an educated guess" << endl;
cin >> c;
cout << "The squareroot of " << a << " is: " << endl;
do
c = (c + (a/c))/2;

while ( c != a/c );

{ cout << c << endl;
}

return 0;
}
</pre>
My problem is that it get remarkably slow around 55ish. Any advice it appreciated

Re: Speed up a square root c++ prog

C^hris L^osinger4-Mar-14 9:56

C^hris L^osinger

4-Mar-14 9:56

c = sqrt(a);

image processing toolkits | batch image processing

Re: Speed up a square root c++ prog

jeron14-Mar-14 9:58

jeron1

4-Mar-14 9:58

I'm guessing your issue is the while(). Comparing two floats can be tricky.

while ( c != a/c );

this[^] link may help.

Re: Speed up a square root c++ prog

leon de boer4-Mar-14 13:34

leon de boer

4-Mar-14 13:34

That is the problem with the Babylonian method you have used.

Paul Hsieh has a very good webpage on everything about square roots but were afraid to ask.

http://www.azillionmonkeys.com/qed/sqroot.html[^]

It includes details most of the techniques from the standard C library, to the faster integers version that NVidia and Quake use.

how to convert word file in to xml using c/c++

krishnaprasad t3-Mar-14 21:53

krishnaprasad t

3-Mar-14 21:53

hi..i have a requirement to write C/c++ application that converts Microsoft Word
(.doc) Documents into XML format. The application should be able to receive/open a Word document and save a XMl file with the same
name, but with the extension .xml..ur valuable suggestions will help me n will be appreciated..thanks

Re: how to convert word file in to xml using c/c++

Richard MacCutchan3-Mar-14 22:04