DaniWeb Forum Index > Software Development > C

Custom pascal triangle ?

Please support our C advertiser: Programming Forums - DaniWeb Sister Site

•

Join Date: Jun 2006

Posts: 7,649

Reputation: ~s.o.s~ has much to be proud of

Solved Threads: 474

~s.o.s~

Offline

Failure as a human

Re: Custom pascal triangle ?

#11

Jul 14th, 2006

THanks to all you ppls help i finally managed to put the code together ( though using two arrays which i couldnt make to one

)

Here is the code i am pasting here for others to have a reference.

Help with Code Tags

(Toggle Plain Text)

[c]
#include "stdafx.h"
 
#include <stdio.h>

constint leftCorner = 3;
constint rightCorner = 4;
constint topElement = 2;
int *oldTriangle = 0;
int *newTriangle = 0;
void displayTriangle (int iteration)
{
if ((iteration % 2) == 1) 
{
for (int i = 1; i <= iteration; ++i)
printf ("%d ", oldTriangle[i-1]);
}
else
{
for (int i = 1; i <= iteration; ++i)
printf ("%d ", newTriangle[i-1]);
}
printf ("\n");
}
 
int buildTriangle (int tmpPascalRow)
{
int tmpRow, elementIndex;
int* src = NULL;
int* dest = NULL;
 
 
oldTriangle[0] = topElement;
displayTriangle (1);
if (tmpPascalRow == 1)
return 1;
 
newTriangle[0] = leftCorner;
newTriangle[1] = rightCorner;
displayTriangle (2);
if (tmpPascalRow == 2)
return 1;
 
for (tmpRow = 3; tmpRow <= tmpPascalRow; ++tmpRow)
{
if ((tmpRow % 2) == 1)
{
dest = oldTriangle;
src = newTriangle;
}
else
{
dest = newTriangle;
src = oldTriangle;
}
 
dest[0] = src[0];
dest[tmpRow-1] = src[tmpRow-2];
for (elementIndex = 1; elementIndex < tmpRow - 1; ++elementIndex)
{
dest[elementIndex] = src[elementIndex] + src[elementIndex - 1];
}
displayTriangle (tmpRow);
}
}
 
int main (void)
{
char inputBuffer[10];
int pascalRow = 0;
int index;
 
fputs ("Enter the number of rows required: ", stdout);
fgets (inputBuffer, sizeof (inputBuffer), stdin);
fflush (stdin);
pascalRow = atoi (inputBuffer);
newTriangle = (int*) calloc (pascalRow, sizeof (int));
oldTriangle = (int*) calloc (pascalRow, sizeof (int));
buildTriangle (pascalRow);
getchar();
return 0;
}
[/c]

THanks to all once again.

Last edited by ~s.o.s~; Jul 14th, 2006 at 3:06 am.

I don't accept change; I don't deserve to live.

Jo Tujhe Jagaaye, Nindein Teri Udaaye Khwaab Hai Sachcha Wahi.
Nindon Mein Jo Aaye Jise To Bhul Jaaye Khawab Woh Sachcha Nahi.
Khwaab Ko Raag De, Nind Ko Aag De

•

Join Date: Jul 2005

Posts: 1,755

Reputation: Lerner is a name known to all

Solved Threads: 283

Lerner

Offline

Posting Virtuoso

Re: Custom pascal triangle ?

#12

Jul 14th, 2006

Use of multidimensional arrays isn't all that difficult, though it can be a bit confusing if you haven't used them before, particularly if you start out using dynamic memory allocation instead of static memory allocation for your first experience. I'm going to use C++ syntax in the following pseudocode since I'm more comfortable with that, but you shouldn't have much trouble converting the C++ syntax to the appropraite C syntax.

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
declare variable, lines, to hold number of lines in the pascals triangle
prompt user to enter number of lines
store number of lines from user in lines
 
declare pascals triangle to be a pointer to pointer to type int like this:
int ** pascalsTri;
 
//allocate memory for an array of pointer to int
pascalsTri = new int *[lines];
 
//for each pointer to int allocate memory for an array of int
for(int i = 0; i < lines; ++i)
  pascalsTri[i] = new int[lines];
 
declare two ints, row and col, to act as indices to access ints in pascalsTri
 
pascalsTri is now equivalent to:
 
int pascalsTri[lines][lines];
 
and any given int in pascalsTri can be refered to individually using pascalsTri[row][col] with the appropriate values of row and col.
 
declare variables to hold the three given values of the triangle; topCorner, rightCorner, leftCorner.
 
prompt user for value of each variable and store it appropriately
 
now use rightCorner, leftCorner, row and col to get the other values of the triangle
 
for each row starting with row 2 up to and including the value lines - 1
  for each col starting with 0 up to and including the value of row 
     if(col == 0)
       pascalTri[row][col] = leftCorner;
     else if(col == row)
       pascalTri[row][col] = rightCorner;
     else
       assign the sum of the int at pascalTri[row - 1][col - 1] plus pascalTri[row -1][col] to the current int with indices row and col
declare variable, lines, to hold number of lines in the pascals triangle
prompt user to enter number of lines
store number of lines from user in lines

declare pascals triangle to be a pointer to pointer to type int like this:
int ** pascalsTri;

//allocate memory for an array of pointer to int
pascalsTri = new int *[lines];

//for each pointer to int allocate memory for an array of int
for(int i = 0; i < lines; ++i)
  pascalsTri[i] = new int[lines];

declare two ints, row and col, to act as indices to access ints in pascalsTri

pascalsTri is now equivalent to:

int pascalsTri[lines][lines];

and any given int in pascalsTri can be refered to individually using pascalsTri[row][col] with the appropriate values of row and col.

declare variables to hold the three given values of the triangle; topCorner, rightCorner, leftCorner.

prompt user for value of each variable and store it appropriately

now use rightCorner, leftCorner, row and col to get the other values of the triangle

for each row starting with row 2 up to and including the value lines - 1
  for each col starting with 0 up to and including the value of row 
     if(col == 0)
       pascalTri[row][col] = leftCorner;
     else if(col == row)
       pascalTri[row][col] = rightCorner;
     else
       assign the sum of the int at pascalTri[row - 1][col - 1] plus pascalTri[row -1][col] to the current int with indices row and col

•

Join Date: Jun 2006

Posts: 7,649

Reputation: ~s.o.s~ has much to be proud of

Solved Threads: 474

~s.o.s~

Offline

Failure as a human

Re: Custom pascal triangle ?

#13

Jul 14th, 2006

Yes the given problem accordnig to me can be solved in three different ways :

1) Using two arrays dynamically allocated (the way which i have done)

2) Using two dimensional array dynamically allocated (the way proposed by Mr. Lerner)

3) Using an array having size (2 * Number of rows of pascal triangle) wherein we use the left part of the array to store the old pascal triangle and the right part of the triangle holding the new row of pascal triangle ( a slight variation of my method).

Hope this serves as a pointer to all the ppl who want to code pascal triangle. Thanks to all.

•

Join Date: Mar 2009

Posts: 1

Reputation: creeping death is an unknown quantity at this point

Solved Threads: 0

creeping death creeping death is offline

Offline

Newbie Poster

Re: Custom pascal triangle ?

#14

Mar 13th, 2009

@~s.o.s~seriously is that much really necessary? moreover gcc is giving many many errors.

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
pas2.c:5: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘leftCorner’
pas2.c:6: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘rightCorner’
pas2.c:7: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘topElement’
pas2.c: In function ‘displayTriangle’:
pas2.c:14: error: ‘for’ loop initial declaration used outside C99 mode
pas2.c:19: error: ‘for’ loop initial declaration used outside C99 mode
pas2.c: In function ‘buildTriangle’:
pas2.c:32: error: ‘topElement’ undeclared (first use in this function)
pas2.c:32: error: (Each undeclared identifier is reported only once
pas2.c:32: error: for each function it appears in.)
pas2.c:37: error: ‘leftCorner’ undeclared (first use in this function)
pas2.c:38: error: ‘rightCorner’ undeclared (first use in this function)
pas2.c: In function ‘main’:
pas2.c:76: warning: incompatible implicit declaration of built-in function ‘calloc’
pas2.c:5: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘leftCorner’
pas2.c:6: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘rightCorner’
pas2.c:7: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘topElement’
pas2.c: In function ‘displayTriangle’:
pas2.c:14: error: ‘for’ loop initial declaration used outside C99 mode
pas2.c:19: error: ‘for’ loop initial declaration used outside C99 mode
pas2.c: In function ‘buildTriangle’:
pas2.c:32: error: ‘topElement’ undeclared (first use in this function)
pas2.c:32: error: (Each undeclared identifier is reported only once
pas2.c:32: error: for each function it appears in.)
pas2.c:37: error: ‘leftCorner’ undeclared (first use in this function)
pas2.c:38: error: ‘rightCorner’ undeclared (first use in this function)
pas2.c: In function ‘main’:
pas2.c:76: warning: incompatible implicit declaration of built-in function ‘calloc’

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
#include <stdio.h>
 
void pascaltriangle(unsigned int n)
{
  unsigned int c, i, j, k;
 
  for(i=0; i < n; i++) {
    c = 1;
    for(j=1; j <= 2*(n-1-i); j++) printf(" ");
    for(k=0; k <= i; k++) {
      printf("%d ", c);
      c = c * (i-k)/(k+1);
    }
    printf("\n");
  }
}
 
int main()
{
  int depth=0;
  printf("Enter depth");
  scanf("%d",&depth);
  pascaltriangle(depth);
  return 0;
}
#include <stdio.h>
 
void pascaltriangle(unsigned int n)
{
  unsigned int c, i, j, k;
 
  for(i=0; i < n; i++) {
    c = 1;
    for(j=1; j <= 2*(n-1-i); j++) printf(" ");
    for(k=0; k <= i; k++) {
      printf("%d ", c);
      c = c * (i-k)/(k+1);
    }
    printf("\n");
  }
}
 
int main()
{
  int depth=0;
  printf("Enter depth");
  scanf("%d",&depth);
  pascaltriangle(depth);
  return 0;
}