c Pointer basic Basics

C   Pointer Basics Technical Questions

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I am sabari, computer science engineer. Here I would like to Share some of my Interview preparation Question you may worked out (compile and run) from these you will come to know some interesting facts on C Pointer Basics,

Basics

Pointer is a variable that holds another variable’s address.

Pointer Example

#include

#include

int main()

{

    int *p,a;

    float *p1,b;

    p=&a;

    p1=&b;

    a=10;

    //clrscr();

    printf("a=%d\n",a);

    printf("a=%d\n",*p);

    /* pointer size*/

    printf("integer pointer size is %d\n",sizeof(p));

    printf("integer size is %d\n",sizeof(a));

    printf("integer pointer size is %d\n",sizeof(p1));

    printf("Float size is %d\n",sizeof(b));

    //printf("welcome");

    return 0;

}

// Function Pointer

#include

#include

void main()

{

int *p; //pointer for a function

int *f();//function  pointer

int a,b,c;

printf("Enter the three numbers:");

scanf("%d %d %d",&a,&b,&c);

p=f(a,b,c);

clrscr();

//printf("a address is :%u",p);

printf("VALUE OF BIG :%d",*p);

getch();

}

int *f(int x,int y,int z)

{

  static int a;

  a=(x

 // a=a*b;

 // printf("a address is :%u",a);

return(&a);

}

String copy

#include

#include

char source1[25],source2[25];

int main()

{

char *sp1,*sp2;

int r;

printf("welcome TO strcompare:\n Enter the sourc1");

scanf("%s",source1);

sp1= source1;

sp2= source2;

while(*sp1)

{

    *sp2=*sp1;

    sp1++;

    sp2++;

}

printf("the copied string is:%s",source2);

return 0;

}

//String compare

#include

#include

char source1[25],source2[25];

int main()

{

char *sp1,*sp2;

int r,c;

clrscr();

printf("welcome TO strcompare:\n Enter the sourc1");

scanf("%s",&source1);

printf("\n Enter the sourc1");

scanf("%s",&source2);

sp1= source1;

sp2= source2;

while(*sp1!='\o')

{

    if(*sp2==*sp1)

    {

    sp1++;

    sp2++;

     c=1;

    }

   else

  {

  printf("the string is not equl");

  *sp1='\o';

  }

  }

  if(c==1)

  {

     printf("the  string is equal");

     }

return 0;

}

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c Technical basics

Hi Blog readers,

I am sabari, computer science engineer. Here I would like to Share some of my Interview preparation Question you may worked out (compile and run) you will come to know some interesting facts on C Basics,

//No of Args

#include

void main()

{                     

int n,a,b,c;

printf("ENter the 3 nos");

n=scanf("%d%d%d",&a,&b,&c);

printf("No of Args:%d",n);

getch();

}

//Ex2 No of Args

#include

#include

int main()

{

int n,a,b,c;

clrscr();

printf("ENter the 3 nos");

n=scanf("%d%d%d",&a,&b,&c);

printf("No of Args:%d",n);

n=printf(printf("First second"););

printf("No of Args:%d",n);

getch();

return 0;

}

//Digit sum(145),1+4+5=10=1+0=1;

#include

#include

void main()

{

 int n;

 clrscr();

 printf("Enter your no");

 scanf("%d",&n);

 n=n%9;

 if(n!=0)

 {

   printf("the digit sum is %d",n);

  }

  else

  {

   printf("the digit sum is %d",9);

   }

 }

 //Input formatting

 #include

#include

void main()

{

                float x = 12.34567;                              /* The keyword `float' declares the number x

                                                                                                                                   to be a real number. */

                clrscr();

                printf("%f\n", x);

                printf("%8.5f\n", x);

                printf("%8.3f\n", x);

                printf("%-8.3f\n", x);

                printf("%9.2e\n", x);            /* printing real number in exponential form */

                printf("%12.4e\n", x);

                printf("%5e\n", x);

                printf("%8.3f\n", -x);

                getch();

}

#include

#include

int main()

{

int n,f;

clrscr();

printf("Enter the NO:");

scanf("%d",&n);

f=fact(&n);

printf("factorial of given is:%d",f);

getch();

return 0;

}

int fact(int *n)

{

int fact=1,i;

 if(*n==0||*n==1)

   return 1;

  else

{

for(i=1;i<=*n;i++)

 {

   fact=fact*i;

 }

 return fact;

}

 

}

//summation

#include

#include

int main()

{

int n,f;

clrscr();

printf("Enter the NO:");

scanf("%d",&n);

f=sum(&n);

printf("summation of given is:%d",f);

getch();

return 0;

}

int sum(int *n)

{

int sum=0,i;

/*

 if(*n==0||*n==1)

   return 1;

  else

  */

{

for(i=0;i<=*n;i++)

 {

   sum=sum+i;

 }

 return sum;

}

 

}

//swapping ( Four different Techniques)

#include

void main()

{

int a,b;

printf("welcome TO swap\nEnter your two nos:\n");

scanf("%d%d",&a,&b);

swap(a,b);

swap(&a,&b);

printf("The swappwe3d nos:%d%d",a,b);

swapt(&a,&b);

printf("The swappwe3d nos:%d%d",a,b);

swapBit(&a,&b);

printf("The swappwe3d nos:%d%d",a,b);

printf("The swappwe3d nos:%d%d",a,b);

swap1(a,b);

getch();

}

//call by value

int swap(int x,int y)

{

 int t;

 t=x;

 x=y;

 y=t;

 printf("The swappwe3d nos:%d%d",x,y);

}

//call by value

int swap1(int x,int y)

{

 x=(x+y)-(y=x);

 printf("The swappwed nos:%d%d",x,y);

}

//call by Ref

int swap(int *x,int *y)

{

 int t;

 t=*x;

 *x=*y;

 *y=t;

}

int swapt(int *x,int *y)

{

 //int t;

 *x=*x+*y;

 *y=*x-*y;

 *x=*x-*y;

}

int swapBit(int *x,int *y)

{

 //int t;

 *x=*x+*y;

 *y=*x-*y;

 *x=*x-*y;

}

//text compresion

#include

#include

void main()

{

FILE *fp,*fd;

char a,b;

int i=1,j;

clrscr();

gotoxy(10,15);

fp=fopen("intxt.txt","r");

fd=fopen("outtxt.txt","w");

fscanf(fp,"%c",&b);

while(!feof(fp))

{

fscanf(fp,"%c",&a);

if(b==a)

{

i++;

}

else

{

if(i>=2)

{

printf("@");

fprintf(fd,"@");

printf("%c%d",b,i);

i=1;

}

else

{

for(j=0;j

{

printf("%c",b);

fprintf(fd,"%c",b);

} i=1;

}}

b=a;

}

if(i>2)

{

printf("@");

fprintf(fd,"%c",a);

i=0;

}

getch();

}