C programming:- Storage classes and Pointers - Part 4



/*Declare three pointer variables to store a character, a character string and an integer respectively. Input values into these variables. Display the address and the contents of each variable.( (MG University NOV 2009)
*/
#include<stdio.h>
main()
{
          int a,*pa;
          char c1,*pc;
          char ch[30],*pch;
          printf("enter an integer,character and a string");
          scanf("%d%1s%s",&a,&c1,ch);
          printf("\nwithout using pointers integer=%d character=%c string=%s",a,c1,ch);
          pa=&a;
          pc=&c1;
          pch=ch;
          printf("\nwith using pointers integer=%d character=%c string=%s",*pa,*pc,pch);
}
/*OUTPUT
enter an integer,character and a string
1 a hello

without using pointers integer=1 character=a string=hello
with using pointers integer=1 character=a string=hello
*/
/*WAP using pointers to multiply two integers. (MG University NOV 2009)*/
#include<stdio.h>
main()
{
          int a,b,*pa,*pb;
         
          printf("enter two integers to multiply:");
          scanf("%d%d",&a,&b);
          printf("\nwithout using pointers res=%d",a*b);
          pa=&a;
          pb=&b;
          printf("\nwith using pointers res=%d",(*pa)*(*pb));
}
/* OUTPUT
enter two integers to multiply:3 4

without using pointers res=12
with using pointers res=12
*/
Swap two numbers using pointers
#include <stdio.h>

int main()
{
   int x, y, *a, *b, temp;

   printf("Enter the value of x and y\n");
   scanf("%d%d", &x, &y);

   printf("Before Swapping\nx = %d\ny = %d\n", x, y);

   a = &x;
   b = &y;

   temp = *a;
   *a   = *b;
   *b   = temp;

   printf("After Swapping\nx = %d\ny = %d\n", x, y);

   return 0;
}

Swapping numbers using call by reference
#include <stdio.h>

void swap(int*, int*);

int main()
{
   int x, y;

   printf("Enter the value of x and y\n");
   scanf("%d%d",&x,&y);

   printf("Before Swapping\nx = %d\ny = %d\n", x, y);

   swap(&x, &y);

   printf("After Swapping\nx = %d\ny = %d\n", x, y);

   return 0;
}

void swap(int *a, int *b)
{
   int temp;

   temp = *a;
   *a   = *b;
   *b  = temp;
}

USING POINTERS WRITE A PROGRAM TO FIND THE BIGGEST OF N NUMBERS IN AN ARRAY ?

#include<stdio.h>
#include<conio.h>
void main()
{ int a[10],i,n,*large,*small;
  clrscr();
  printf("\nEnter number of elements of the array:");
  scanf("%d",&n);
  printf("\nEnter the elements:");
  for(i=0;i<n;i++)
     {  scanf("%d",&a[i]);
     }
  large=a;
  small=a;
  for(i=0;i<n;i++)
  { if(*large<a[i])
      { large=&a[i];
      }
    if(*small>a[i])
      { small=&a[i];
      }
   }
   printf("\nThe largest number is %d",*large);
   printf("\nThe smallest number is %d",*small);
   getch();
 }

WRITE A C PROGRAM TO COUNT THE NUMBER OF VOWELS IN AN ARRAY OF CHARACTERS USING POINTERS ?

#include<conio.h>
#include<stdio.h>
#include<string.h>
void main()
{
char *s,a[50];
int i=0;
clrscr();
printf("ENTER THE STRING   ");
gets(a);
s=a;
while(*s!='\0')
{
switch(*s)
{
case 'a':i++;
break;
case 'e':i++;
break;
case 'i':i++;
break;
case 'o':i++;
break;
case 'u':i++;
break;
case 'A':i++;
break;
case 'E':i++;
break;
case 'I':i++;
break;
case 'O':i++;
break;
case 'U':i++;
break;
}
s++;
}
printf("THE NO. OF VOWELS = %d ",i);
getch();
}
.. Using pointers ,write a C program to add  two square matrices
Without pointers:
#include<stdio.h>
main()
{
          int a[10][10],b[10][10],c[10][10];
          int i,j,m,n;
          printf("enter the order of matrices:");
          scanf("%d%d",&m,&n);
          printf("enter mat A elements");
          for(i=0;i<m;i++)
          {
                   for(j=0;j<n;j++)
                   {
                             scanf("%d",&a[i][j]);
                   }
          }
          printf("enter mat B elements");
          for(i=0;i<m;i++)
          {
                   for(j=0;j<n;j++)
                   {
                             scanf("%d",&b[i][j]);
                   }
          }
          printf("\nresultant mat C:\n");
          for(i=0;i<m;i++)
          {
                   for(j=0;j<n;j++)
                   {
                             c[i][j]=a[i][j]+b[i][j];
                             printf("%d ",c[i][j]);
                   }
                   printf("\n");
          }
}
With pointers:
#include<stdio.h>
main()
{
          int a[10][10],b[10][10],c[10][10];
          int i,j,m,n;
          printf("enter the order of matrices:");
          scanf("%d%d",&m,&n);
          printf("enter mat A elements");
          for(i=0;i<m;i++)
          {
                   for(j=0;j<n;j++)
                   {
                             scanf("%d",(*(a+i)+j));
                   }
          }
          printf("enter mat B elements");
          for(i=0;i<m;i++)
          {
                   for(j=0;j<n;j++)
                   {
                             scanf("%d",(*(b+i)+j));
                   }
          }
          printf("\nresultant mat C:\n");
          for(i=0;i<m;i++)
          {
                   for(j=0;j<n;j++)
                   {
                             *(*(c+i)+j)= *(*(a+i)+j)+ *(*(b+i)+j);
                             printf("%d ",*(*(c+i)+j));
                   }
                   printf("\n");
          }
}
Using functions:
#include<stdio.h>
void readmat(int pa[10][10],int p,int q);                //pass matrix and its order
void sum(int pa[10][10],int pb[10][10],int p,int q);         /*pass two matrices and its order*/
void disp(int pa[10][10],int p,int q);                 //pass matrix and order
int a[10][10],b[10][10],c[10][10];
int i,j;
main()
{
         
          int m,n;
          printf("enter the order of matrices:");
          scanf("%d%d",&m,&n);
          printf("enter mat A elements");
          readmat(a,m,n);
          printf("enter mat B elements");
          readmat(b,m,n);
          sum(a,b,m,n);
          printf("mat A:\n");
          disp(a,m,n);
          printf("mat B:\n");
          disp(b,m,n);
          printf("\nresultant mat C:\n");
          disp(c,m,n);
}
void readmat(int pa[10][10],int p,int q)
{
          for(i=0;i<p;i++)
          {
                   for(j=0;j<q;j++)
                   {
                             scanf("%d",(*(pa+i)+j));
                   }
          }
}
void sum(int pa[10][10],int pb[10][10],int p,int q)
{
          for(i=0;i<p;i++)
          {
                   for(j=0;j<q;j++)
                   {
                             *(*(c+i)+j)= *(*(a+i)+j)+ *(*(b+i)+j);
                            
                   }
                  
          }
}
void disp(int pa[10][10],int p,int q)
{
          for(i=0;i<p;i++)
          {
                   for(j=0;j<q;j++)
                   {
                             printf("%d ",*(*(pa+i)+j));
                   }
                   printf("\n");
          }
}
/*OUTPUT
enter the order of matrices:2 2
enter mat A elements 1 2 3 4
enter mat B elements1 1 1 1
mat A:
1 2
3 4
mat B:
1 1
1 1

resultant mat C:
2 3
4 5
*/
WAP using pointers to sort the given list of numbers in descending order. .(MG University NOV 2010)
Without pointers:
#include <stdio.h>
main()
{
   int arr[30],i,j,tmp,n;
    printf("Enter limit of numbers : ");
   scanf("%d",&n);
   for(i=0;i<n;i++)
      scanf("%d",&arr[i]);

   for(i=0;i<n-1;i++)
   {
    for(j=0;j<n-1;j++)
          {
           if( arr[j] < arr[j+1])
           {
                    tmp = arr[j];
                    arr[j] = arr[j+1];
                   arr[j+1] = tmp;
           }
          }
   }

   printf("\n\nAfter Sorting in descending order\n");
   for(i=0;i<n;i++)
      printf("%d\n",arr[i]);

     
}
/*OUTPUT
Enter limit of numbers : 5
13 2 1 5 34


After Sorting in descending order
34
13
5
2
1
*/
With pointers:
#include <stdio.h>
main()
{
   int arr[30],i,j,tmp,n;
    printf("Enter limit of numbers : ");
   scanf("%d",&n);
   for(i=0;i<n;i++)
      scanf("%d",arr+i);

   for(i=0;i<n-1;i++)
   {
    for(j=0;j<n-1;j++)
          {
           if( *(arr+j) < *(arr+j+1))
           {
                    tmp = *(arr+j);
                    *(arr+j) = *(arr+j+1);
                   *(arr+j+1) = tmp;
           }
          }
   }

   printf("\n\nAfter Sorting in descending order\n");
   for(i=0;i<n;i++)
      printf("%d\n",*(arr+i));

     
}
/*OUTPUT
Enter limit of numbers : 5
13 2 1 5 34


After Sorting in descending order
34
13
5
2
1
*/
Write a C function that receives a number n and returns a pointer to a character string containing the name of the corresponding day. The day names should be stored in a static table of character strings local to the function. (MG University MAY 2009)

#include<stdio.h>
char* fun(int a);
main()
{
          int n;
          char *ch;
          printf("enter a number(1-7)");
          scanf("%d",&n);
          ch=fun(n);
          printf("output-->%s",ch);
}
char* fun(int a)
{
char c[10][10]={"monday","tuesday","wednesday","thursday","friday","saturday","sunday"};

          switch(a)
          {
                   case 1: return(c[0]);
                             break;
                   case 2: return(c[1]);break;
                   case 3: return(c[2]);break;
                   case 4: return(c[3]);break;
                   case 5: return(c[4]);break;
                   case 6: return(c[5]);break;
                   case 7: return(c[6]);break;
                   default :printf("invalid"); break;
          }       
}
/*
enter a number(1-7)4
output-->thursdaystudent@ubuntu:~$ ./a.out
enter a number(1-7)1
output-->mondaystudent@ubuntu:~$ ./a.out
enter a number(1-7)9
invalidoutput-->(null)student@ubuntu:~$ ./a.out
enter a number(1-7)6
*/
WAP to find the largest word of a given sentence, using pointers.
Pgm Without pointers (try it with pointers)
#include<stdio.h>
#include<string.h>

main()
{
          char sen[30];
          char s[30][30],s1[30];
          int c,i,j,k,m,l1,l2;
         
         
          printf("enter a sentence:");
          gets(sen);
          c=strlen(sen);
          j=0;k=0;
          for(i=0;i<c;i++)
          {
                   while(sen[i]!=' ')
                   {
                             s[j][k]=sen[i]; i++;k++;
                   }
                   if(sen[i]==' ')
                   {        s[j][k]='\0';j++; k=0;}
          }
          m=j;
          printf(" 2d array: ");
          for(i=0;i<m;i++)
          printf("%s\n",s[i]);

          for(i=0;i<m;i++)
          {
                  
                   printf(" %s len= %d\n",s[i],strlen(s[i]));
          }
          l1=strlen(s[0]);
          for(i=0;i<m;i++)
          {
                   if(l1<strlen(s[i]))
                             {l1=strlen(s[i]);
                             strcpy(s1,s[i]);}
                  
          }
         
         
          printf("longest word= %s len= %d\n",s1,l1);
         
         
                  
}
/*
student@ubuntu:~$ ./a.out
enter a sentence:hai students study well
 2d array: hai
students
study
well
 hai len= 3
 students len= 8
 study len= 5
 well len= 4
longest word= students len= 8*/

delete duplicate words in a string

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

main()
{
    char a[100], b[20][20];
    int i, j = 0, k = 0, n, m;

    printf("enter the string\n");
    scanf("%[^\n]", a);
    for (i = 0;a[i] != '\0';i++)
    {
        if (a[i] == ' ')
        {
            b[k][j] = '\0';
            k++;
            j = 0;
        }
        else
        {
            b[k][j] = a[i];
            j++;
        }
    }
    b[k][j] = '\0';
    for (i = 0;i <= k;i++)
    {
        for (j = i + 1;j <= k;j++)
        {
            if (strcmp(b[i], b[j]) == 0)
            {
                for (m = j;m <= k;m++)
                    strcpy(b[m], b[m + 1]);
                k--;
            }
        }
    }
    for (n = 0;n <= k;n++)
    {
        printf("%s\n", b[n]);
    }
}

/*       OUTPUT
enter the string
hai hai students. you should study study well.
hai
students.
you
should
study
well.
*/

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