Re: A General Problem - C / C++ / MFC Discussion Boards

dipuks wrote:
i am using the functions, _write and _ read.

See here and here.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

For opening binary file use CreateFile [^] with OPEN_EXISTING flag.

For reading the file use ReadFile [^]

For writing the file use WriteFile [^]

Величие не Бога может быть недооценена.

Hi,
I have the following program.
I want to use char array at the end of while loop so that after while loop if i use printf() statement it will be printed.I have already copy the directory in an char array.Actually i am something confusing at this time and cann't solve the problem.

#include<windows.h>
#include<string.h>
#include<stdio.h>

int main()
{
int length1,length2;
WIN32_FIND_DATA FindFileData;
HANDLE hFind = INVALID_HANDLE_VALUE;
char DirSpec[MAX_PATH + 1];
DWORD dwError;
char dirpath[MAX_PATH];

printf("Enter the path of directory: ");
gets(dirpath);

printf ("Target directory is %s\n",dirpath);
strncpy (DirSpec, dirpath, strlen(dirpath)+1);
strncat (DirSpec, "\\*", 3);

hFind = FindFirstFile(DirSpec, &FindFileData);

if (hFind == INVALID_HANDLE_VALUE)
{
printf ("Invalid file handle. Error is %u\n", GetLastError());
return (-1);
}
else
{

length1=sizeof(FindFileData.cFileName);
char firstdir[length1];
strcpy(firstdir,FindFileData.cFileName);
printf("First file name is %s\n",firstdir);
while (FindNextFile(hFind, &FindFileData) != 0)
{
length2=sizeof(FindFileData.cFileName);
char otherdir[length2];
strcpy(otherdir,FindFileData.cFileName);
printf("Other dir is:%s\n",otherdir);
}
/* ****************************************************
* here i want a char array *
* printf("All dir except first is:%s",array); *
* *
****************************************************/

dwError = GetLastError();
FindClose(hFind);
if (dwError != ERROR_NO_MORE_FILES)
{
printf ("FindNextFile error. Error is %u\n", dwError);
return (-1);
}
}
return (0);
}
I have commented the line where i want the char array.Actually i want this array outside while loop.

Please post your code withing the code block.
You are more likely to get and answer if you do that.

ravi 12 wrote:
char otherdir[length2]

You cannot create an array with a variable (length2) as its size.
You need to have a constant instead.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Hi «_Superman_»,
thank you very much for your suggestion.You are right that i must create a constant size array.thanks

Are you wanting a char array of all files found in the while() loop by the FindFirstFile()/FindNextFile() pair? Unless you have an aversion against it, use std::vector or std::list.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Hi DavidCrow,
Thanks for your suggestion.Yes i want a char array of all files found in the while() loop by the FindFirstFile()/FindNextFile() pair.

Perhaps «_Superman_» overlooked the difference between c and c++ when it came to dynamically sized array declarations - they work just fine here too.

Um, this is really very easy.
You need to declare somewhere to hold a string.
After each new filename has been retrieved it's tacked onto the end of the existing string
When the loop's over the string is printed.

I can think of at least 3 ways around this mountain, though (surprise, surprise) went for the easiest/quickest/dodgiest (is that even a word?) way.

1. Declare a new var in main and initialize to 4096 times "\0" (since I'm testing in C:\ and I know there to be under 4kb worth of file/folder names there)

char finalString[4096];

2. Add to it each time through the loop

while (FindNextFile(hFind, &FindFileData) != 0)
{
    strcat(finalString, FindFileData.cFileName);
    strcat(finalString, "\n");
}

3. Print it out

printf("%s\n", finalString);

The other two ways that come to mind are:

1. Dynamically resizing the memory used to hold the final string.
2. Getting a count of the number of dir-entries, then creating an array of char* with that many entries. You then alloctae some memory, point dirEntryArray[curEntryNum] at this memory, and make sure you copy the current filename into said mem.

You can probably see why I went for the 'coding-horrors' way. Sigh | :sigh:

EDIT: ah crap! See, that's why David is an MVP, and I'm not. Sniff | :^)

hi enhzflep,
very very thank of you for your suggestion.Now it works fine.Actually i was useing strcpy() function instead of strcat() function.I don't know why i was unable to do that.Thanks again..........

I think it will better if we can use heap allocation instead of stack for 4k, because, these 4k allocations finally leads to stack overflow. Sniff | :^)

.

Ravi you can follow which ever method according to the need.
If you follow David's method then it will be less error prone and more maintainable Smile | :)

but enhzflep's method is much faster Smile | :)

Величие не Бога может быть недооценена.

modified on Friday, October 30, 2009 4:38 AM

I am trying to write a program as a math tutor. Can someone look at this code. I keep getting errors on int and pointer as well as telling me the switch case has illegal pointer.

Thanks, any advice would be greatful.

#include <stdio.h>
#include <stdlib.h>


#define SENT 4 //"Quit" menu choice


/*  Function Prototypes */


	void DisplayMenu (void);
	void GetMenuChoice (void);
	void Gen2Rand (int*r1, int*r2);
	void DrillOneProb (int*c, int*r1, int*r2);






/*============Mainline Procedures===============*/

int main (void)
{
	int	   c;   //Menu Choice (1-4)
	int   r1,  //First Random Integer:  2-12 inclusive
	      r2;  //Second Randon Integer:  2-12 inclusive


}

/*===========CHILD FUNCTIONS===============*/

/*  Display Title and Menu */

void DisplayMenu (void)

	{
		printf("MENU OF OPERATIONS\n\n");
		printf("1. Addition.\n");
		printf("2. Subtraction.\n");
		printf("3. Multiplication.\n");
		printf("4. Quit.\n\n");

    }


/* Get Menu Choice */

void GetMenuChoice (void)

	{
		int c;
		printf ("Enter the number of the operation to try (1-4):\n");
		scanf ("%d", &c);
		while
			 (c<1 || c>SENT)
				printf("\aInput value is out of range.\n");


	}

/* Generate and return 2 integers between 2-12 inclusive */

void Gen2Rand (int *r1p, int *r2p)

	{
		int c;
		c=0;

		if (c>=1 && c<SENT)

		int r1; // First random number
		int r2; //Second random number

		r1 = 2 + rand() %11;
		r2 = 2 + rand() %11;

	   *r1p = r1;
	   *r2p = r2;

	   printf("Program complete\n");

	}

/* Display two random numbers and ask user what the answer would be after the chosen operation*/

void DrillOneProb (int *c, int *r1, int *r2)

{
		int CorAns, //Correct Answer
			Reply;  // Users Reply

			{
			printf("\nWhat is %d", & r1);

			r1 = 2 + rand() % 11;
			}


	switch (c);
	{
		case '1':  1 = +; break;
		CorAns = r1 + r2;

		case '2':  2 = -; break;
		CorAns = r1 - r2;

		case '3':  3 = x; break;
		CorAns = r1 x r2;

	}

	printf("%d ?  %d\n", r2, Reply);

   if
  		Reply = CorAns
	   		{
			   printf("Yes, that is correct. Good Job!");
			}

		else
			printf("No, the correct answer is: %d", CorAns);
			printf("\n\n");

return (c);




    print_menu(); //Print the menu option, and configure some needed things.


    return (0); //The end of our simple game.

kbury wrote:
switch (c);

This must be switch (c) without the ;

I also believe that it must actually be switch (*c)

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Thanks, I just changed and it fixed that part.

kbury wrote:
1 = +;

kbury wrote:
2 = -;

kbury wrote:
3 = x;

kbury wrote:
CorAns = r1 x r2;

kbury wrote:
if
Reply = CorAns

I think you should read very carefully a syntax reference of the C programming language.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

I am only trying to follow a flow chart given and it is very confusing. Thank you

While following the flow, you shouldn't forget there is also the syntax... Roll eyes | :rolleyes:

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

I am stuck with this section of my code so far: error codes: expected int and got pointer to int and operands of = illegaltype pointer to int and int

/* Display two random numbers and ask user what the answer would be after the chosen operation*/

void DrillOneProb (int*c, int*r1, int*r2)

{
		int CorAns, //Correct Answer
			Reply;  // Users Reply

			{
			printf("\nWhat is %d",r1);	1st error		                scanf("%d", r1);

			r1 = 2 + rand() % 11;           2nd error
			}

kbury wrote:
printf("\nWhat is %d",r1);

change to

printf("\nWhat is %d", *r1);

kbury wrote:
r1 = 2 + rand() % 11;

change to

*r1 = 2 + rand() % 11;

The above steps, however just fix compiler errors...I don't know if the semantic will be correct.

BTW what about a good C language programming book?
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

change to

printf("\nWhat is %d", *r1); (I already changed this)I figured that out.

kbury wrote:
r1 = 2 + rand() % 11;

change to

*r1 = 2 + rand() % 11; (This defineately fixed this.

The above steps, however just fix compiler errors...I don't know if the semantic will be correct.

switch (c)

	{     (states that this is illegal type pointer to int in       switch expression.)

		case '1':
		  	printf("+");
		   	CorAns = r1 + r2;  (operands of + have illegal of 'pointer to int' and 'pointer to int')

		  break;

kbury wrote:
CorAns = r1 + r2;

change to

CorAns = *r1 + *r2;

The real solution, however, would be reading the f*#?n' book. Big Grin | :-D

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

I do not believe that has been in any of the chapters that we have read so far, but I will look again at the latest chapter because each assignment is associated with that chapter.

and what about the brace

I guess you're able to guess now.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

I am developing an application with three splitter panes, leftpane,right pane and bottom pane.
leftpane consists of a tree control, by clicking on the tree item, correspoding Dialog displayes in the right pane. For one tree item, by selecting it , i need to display another application by running winExec(), in right pane. I am facing problem at fitting this result application in the rightpane..I have tried with variuos Show window parameter for Winexec() call, but i failed.

thanks,
hema.

WinExec() spawns a new process.
If you want to show that in another application you need to create a relationship between the two applications.
You can do that using SetParent[^] and then use MoveWindow[^] to place it correctly in the right pane.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)