[c]Pointers - Tilted Forum Project Discussion Community

zero2 · 12-17-2006, 05:25 PM

I kind of hate to ask so many times for help, but I'm really struggling at this.

I need to write a function, that allows a user to enter a string -- a pointer to char, and converts it to binary digit string or another pointer to char.

For instance, a user can type in any of the following, and that would be acceptable values.

a)"10100010001111"
b)" 001011100"
c)"11110010 "

My output is supposed to look like this:

Enter a binary string to continue or q to quit:
123ab46
The given string is not convertible!

Enter a binary string to continue or q to quit:
1010110100
The given string is converted to
1010110100

Enter a binary string to continue or q to quit:
q
Thank you!

So far this is what I got for my code, and after looking at it, I know it's really really wrong. I think where I'm going wrong is that instead of a loop, perhaps a switch statement would be better, but maybe I'm wrong. I also need to use pointers, but since I'm more comfortable with arrays, I want to try it with arrays, and later figure out how to do it with pointers.

Code:

#include <stdio.h>
/* Function Declaration */
int convertToBinaryVersionA(char cAry[]);

int main(void)
{
	int iA;
	char cAry[81];
	
	iA = convertToBinaryVersionA(cAry);
	return 0;
}

/**
* Function Name: convertBinaryVersionA()
*
*/
int convertToBinaryVersionA(char cAry1[])
{
	int i, j;
	int iSize;
	char cTest[81];
	int iVal;	
	
	printf("Enter a binary string to continue or q to quit: ");
	gets(cAry1);
	
	j = 0;
	
	for (i = 0; i < iSize; i++)
		{
			if ( cAry1 [i] == '0' || cAry1 [i] == '1' ) //testing if value is a binary digit
					 {
							cTest [j] = cAry1[i];//storing binary digit into array
							j++;
							iVal = 1;//return 1 if input is a binary #
	
						}
			else
				{    
                             for ( i= 0; i < iSize; i++)
	                            {
		                          printf("%3c", cAry1[i]);
	                            }
                            printf("The given string is not convertible");
					iVal = 0;//return 0 if input is not a binary #
				}
		}
      printf("The given string is converted to: ");	
	for ( j= 0; j < iSize; j++)
	{
		printf("%3c", cTest[j]);//values
	}
	return iVal;
}

Rekna · 12-18-2006, 06:50 AM

You are converting from binary to binary? That doesn't make much sense. If you are going from binary to decimal that is pretty easy. Just loop over the digits and add 1 to a counter if the digit is a 1. When the loop moves to the next digit multiply by 2.

Are you doing all these problems for a class?

zero2 · 12-20-2006, 09:09 PM

Actually it looks like the formatting in my previous post where, what is acceptable values got messed up, but there are actually spaces in example b, and c, but it's hard to tell.

I need to store the values into a array/pointer, then store the values from the first array back into another array, with the condition that the values are binary digits.

So lets say a user enters: space, space, 1, 0, 1, 1, 0, 0

'', '', '1', '0', '1', '1', '0', '0'

The first array would grab the data such as:

cAry[0] = ''
cAry[1] = ''
cAry[2] = '1'
cAry[3] = '1'
cAry[4] = '0'
cAry[5] = '0'
cAry[6] = '\n'

The second character array, needs to grab only binary numbers:

cAryBinary[0] = '1'
cAryBinary[1] = '1'
cAryBinary[2] = '0'
cAryBinary[3] = '1'
cAryBinary[4] = '0'
cAryBinary[5] = '\n'

So far this is what I have, it's far from being done, but one problem I've come across, is how to have the program ask: Enter a binary string to continue or q to quit, and only when the q is entered does the program stop asking that question.

I was thinking of doing a while loop, that asks:

while (*(cPtr + 0) !=q )
do ...
but that doesn't seem to work.

Code:

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

int main(void)
{
	int iSize;
	char *cPtr;
	

	printf("\nEnter estimate size of string ");
	scanf("%d", &iSize);
	getchar();//clears input buffer
	cPtr = (char * ) malloc (iSize * sizeof(char));
	printf("Enter a binary string to continue or q to quit:");
	gets(cPtr);

	if ( *(cPtr+ 0) == 'q' )
	{
		printf("Thank You!\n");
	}
	else if (*(cPtr + 0) == '0' || *(cPtr + 0) == '1' )
	{
		printf("The given string is converted to %s\n", cPtr);
	}
	else
	{
		printf("The given string is not convertible!\n");
	}
	return 0;

}

Rekna · 12-20-2006, 09:53 PM

Quote:

Originally Posted by zero2

Actually it looks like the formatting in my previous post where, what is acceptable values got messed up, but there are actually spaces in example b, and c, but it's hard to tell.

I need to store the values into a array/pointer, then store the values from the first array back into another array, with the condition that the values are binary digits.

So lets say a user enters: space, space, 1, 0, 1, 1, 0, 0

'', '', '1', '0', '1', '1', '0', '0'

The first array would grab the data such as:

cAry[0] = ''
cAry[1] = ''
cAry[2] = '1'
cAry[3] = '1'
cAry[4] = '0'
cAry[5] = '0'
cAry[6] = '\n'

The second character array, needs to grab only binary numbers:

cAryBinary[0] = '1'
cAryBinary[1] = '1'
cAryBinary[2] = '0'
cAryBinary[3] = '1'
cAryBinary[4] = '0'
cAryBinary[5] = '\n'

So far this is what I have, it's far from being done, but one problem I've come across, is how to have the program ask: Enter a binary string to continue or q to quit, and only when the q is entered does the program stop asking that question.

I was thinking of doing a while loop, that asks:

while (*(cPtr + 0) !=q )
do ...
but that doesn't seem to work.

Code:

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

int main(void)
{
	int iSize;
	char *cPtr;
	

	printf("\nEnter estimate size of string ");
	scanf("%d", &iSize);
	getchar();//clears input buffer
	cPtr = (char * ) malloc (iSize * sizeof(char));
	printf("Enter a binary string to continue or q to quit:");
	gets(cPtr);

	if ( *(cPtr+ 0) == 'q' )
	{
		printf("Thank You!\n");
	}
	else if (*(cPtr + 0) == '0' || *(cPtr + 0) == '1' )
	{
		printf("The given string is converted to %s\n", cPtr);
	}
	else
	{
		printf("The given string is not convertible!\n");
	}
	return 0;

}

There are lots of ways to do that but yours is close to right. You don't need the +0, and i'd avoid using the * operator. Instead do something like

//input cptr

while(cptr[0]!='q' || cptr[0]!='Q')
{
//process string

//input cptr
}

Also just an fyi. the command break; will exit the innermost loop and the command exit(int retval); will quit the program and return the value retval to the calling program. These can be used for termination.

Sorry for not giving you lots of code but I think it's important that you learn the stuff yourself by trying things out.

zero2 · 12-21-2006, 08:04 PM

Thank You Rekna. I liked the code that you had where you test for lowercase q or uppercase Q, that was something that I didn't think off.

I also ran into a problem, when I added the while loop, I wasn't able to ask the user the size of the pointer after the first iteration.

So my output looked like this:
=====First Time Run==========
Enter an estimate of size of string: 7
Enter a binary string to continue or q to quit:
123ab46
The given string is not convertible!
======Second Time Run==========
Enter a binary string to continue or q to quit: 7
123ab46
The given string is not convertible!

Here's my latest code, hopefully I'm doing something right here:

Code:

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

void convertToBinaryVersionA();

int main(void)
{
	convertToBinaryVersionA();
		return 0;
}

void convertToBinaryVersionA()
{
	char *cPtr;
	int iSize;
	int i;
	char *cBinary;
	int j = 0;
	int iCount;
	
	printf("Enter an estimate of size of string: ");
	scanf("%d", &iSize);
	
	getchar();
	cPtr =  (char *) malloc (iSize * sizeof(char));
	printf("Enter a binary string to continue or q to quit: ");
	gets(cPtr);
	
	cBinary = (char *) malloc (iSize * sizeof(char));
	
	for (i = 0; i < iSize; i++)
		{
			if( * (cPtr + 0) == 'q' || * (cPtr + 0) == 'Q')
				{
					printf("Thank You!\n");
				}
			else if ( * (cPtr + i) == '0' || * (cPtr + i) == '1' )
				{
					cBinary[j] = cPtr[i];
					j++;
					iCount = 0;
				}
			else
				{
					iCount = 1;
					
				}
		}
		if ( iCount == 0 )
		{
			printf("The converted string is: %s", cBinary);
		}
		else
		{
			printf("The inputed string is not convertible!\n");
		}
	
	return;
}

Rekna · 12-21-2006, 09:23 PM

Quote:

Originally Posted by zero2

Thank You Rekna. I liked the code that you had where you test for lowercase q or uppercase Q, that was something that I didn't think off.

I also ran into a problem, when I added the while loop, I wasn't able to ask the user the size of the pointer after the first iteration.

So my output looked like this:
=====First Time Run==========
Enter an estimate of size of string: 7
Enter a binary string to continue or q to quit:
123ab46
The given string is not convertible!
======Second Time Run==========
Enter a binary string to continue or q to quit: 7
123ab46
The given string is not convertible!

Here's my latest code, hopefully I'm doing something right here:

Code:

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

void convertToBinaryVersionA();

int main(void)
{
	convertToBinaryVersionA();
		return 0;
}

void convertToBinaryVersionA()
{
	char *cPtr;
	int iSize;
	int i;
	char *cBinary;
	int j = 0;
	int iCount;
	
	printf("Enter an estimate of size of string: ");
	scanf("%d", &iSize);
	
	getchar();
	cPtr =  (char *) malloc (iSize * sizeof(char));
	printf("Enter a binary string to continue or q to quit: ");
	gets(cPtr);
	
	cBinary = (char *) malloc (iSize * sizeof(char));
	
	for (i = 0; i < iSize; i++)
		{
			if( * (cPtr + 0) == 'q' || * (cPtr + 0) == 'Q')
				{
					printf("Thank You!\n");
				}
			else if ( * (cPtr + i) == '0' || * (cPtr + i) == '1' )
				{
					cBinary[j] = cPtr[i];
					j++;
					iCount = 0;
				}
			else
				{
					iCount = 1;
					
				}
		}
		if ( iCount == 0 )
		{
			printf("The converted string is: %s", cBinary);
		}
		else
		{
			printf("The inputed string is not convertible!\n");
		}
	
	return;
}

Don't ask the user the size of the string, use input should always be kept to a minimum. Instead just create a buffer for the string that is bigger than a user would enter (say 1000 or 10000 characters). Asking the user what size the string is gives the user an unnecessary burden. In addition if the user is wrong and they make a string that is to small then your program will more than likely crash, or worse a malicious user could use that program to do bad things. There are lots of issues dealing with buffer overrun errors that you shouldn't worry about at this time. That is a much more advanced topic. For now just use a very large array that way you don't have to use malloc instead just use an array.

Also if and when you use malloc make sure you free the memory also. Failure to free it causes memory leaks.

12-17-2006, 05:25 PM	#1 (permalink)
zero2 Junkie	[c]Pointers I kind of hate to ask so many times for help, but I'm really struggling at this. I need to write a function, that allows a user to enter a string -- a pointer to char, and converts it to binary digit string or another pointer to char. For instance, a user can type in any of the following, and that would be acceptable values. a)"10100010001111" b)" 001011100" c)"11110010 " My output is supposed to look like this: Enter a binary string to continue or q to quit: 123ab46 The given string is not convertible! Enter a binary string to continue or q to quit: 1010110100 The given string is converted to 1010110100 Enter a binary string to continue or q to quit: q Thank you! So far this is what I got for my code, and after looking at it, I know it's really really wrong. I think where I'm going wrong is that instead of a loop, perhaps a switch statement would be better, but maybe I'm wrong. I also need to use pointers, but since I'm more comfortable with arrays, I want to try it with arrays, and later figure out how to do it with pointers. Code: #include <stdio.h> /* Function Declaration / int convertToBinaryVersionA(char cAry[]); int main(void) { int iA; char cAry[81]; iA = convertToBinaryVersionA(cAry); return 0; } /* * Function Name: convertBinaryVersionA() * */ int convertToBinaryVersionA(char cAry1[]) { int i, j; int iSize; char cTest[81]; int iVal; printf("Enter a binary string to continue or q to quit: "); gets(cAry1); j = 0; for (i = 0; i < iSize; i++) { if ( cAry1 [i] == '0' \|\| cAry1 [i] == '1' ) //testing if value is a binary digit { cTest [j] = cAry1[i];//storing binary digit into array j++; iVal = 1;//return 1 if input is a binary # } else { for ( i= 0; i < iSize; i++) { printf("%3c", cAry1[i]); } printf("The given string is not convertible"); iVal = 0;//return 0 if input is not a binary # } } printf("The given string is converted to: "); for ( j= 0; j < iSize; j++) { printf("%3c", cTest[j]);//values } return iVal; }

12-20-2006, 09:09 PM	#3 (permalink)
zero2 Junkie	Actually it looks like the formatting in my previous post where, what is acceptable values got messed up, but there are actually spaces in example b, and c, but it's hard to tell. I need to store the values into a array/pointer, then store the values from the first array back into another array, with the condition that the values are binary digits. So lets say a user enters: space, space, 1, 0, 1, 1, 0, 0 '', '', '1', '0', '1', '1', '0', '0' The first array would grab the data such as: cAry[0] = '' cAry[1] = '' cAry[2] = '1' cAry[3] = '1' cAry[4] = '0' cAry[5] = '0' cAry[6] = '\n' The second character array, needs to grab only binary numbers: cAryBinary[0] = '1' cAryBinary[1] = '1' cAryBinary[2] = '0' cAryBinary[3] = '1' cAryBinary[4] = '0' cAryBinary[5] = '\n' So far this is what I have, it's far from being done, but one problem I've come across, is how to have the program ask: Enter a binary string to continue or q to quit, and only when the q is entered does the program stop asking that question. I was thinking of doing a while loop, that asks: while ((cPtr + 0) !=q ) do ... but that doesn't seem to work. Code: #include <stdio.h> #include <stdlib.h> int main(void) { int iSize; char cPtr; printf("\nEnter estimate size of string "); scanf("%d", &iSize); getchar();//clears input buffer cPtr = (char * ) malloc (iSize * sizeof(char)); printf("Enter a binary string to continue or q to quit:"); gets(cPtr); if ( (cPtr+ 0) == 'q' ) { printf("Thank You!\n"); } else if ((cPtr + 0) == '0' \|\| *(cPtr + 0) == '1' ) { printf("The given string is converted to %s\n", cPtr); } else { printf("The given string is not convertible!\n"); } return 0; }

12-18-2006, 06:50 AM	#2 (permalink)
Rekna Junkie	You are converting from binary to binary? That doesn't make much sense. If you are going from binary to decimal that is pretty easy. Just loop over the digits and add 1 to a counter if the digit is a 1. When the loop moves to the next digit multiply by 2. Are you doing all these problems for a class?