Programming Questions

Q:

Point out the error, if any, in the following program.

# include "stdio.h"

main()

{

     FILE *fp;

     char str[80];

     fp = fopen ("trail", "r");

     while (!feof (fp))

    {

           fgets (str, 80, fp);

           puts (str);

     }

     fclose (fp);

}

Answer

The last line from the file "trial" would be read twice. To avoid this, ues:


       While ( fgets (str, 80, fp) ! = NULL)


               puts (str);

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Q:

Indicate what would the SWAP macro be expanded to on preprocessing. Would the code compile?

#define SWAP (a, b, c ) (c t; t = a, a = b, b = t; )

main()

{

    int x = 10, y = 20;

    SWAP (x, y, int );

    printf ( " %d%d ", x, y);

}

Answer

( int t ; t = a, a = b, b = t ;);


This code won't compile since declaration of t cannot occur within parentheses.


 

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Q:

Point out the error, if any, in the while loop.

main()

{

  int i = 1;

  while ()

  {

     printf ( "%d", i++);

     if (i >10) 

     break ;

   }

}

Answer

The condition in the while loop is a must.

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Q:

public static void main string[] args Meaning is?

Answer

Here in this declaration public static void main string[] args, each keyword has its importance.


 


1. public - Here public is an access specifier which allows the main method to be accessible everywhere.


 


2. static - static helps the main method to get loaded without getting called by any instance/object.


 


3. void - void clarifies that the main method will not return any value.


 


4. main - It's the name of the method.


 


5. String[] args - Here we are defining a String array to pass arguments at the command line. args is the variable name of the String array.

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Q:

There is a mistake in the following code. Add a statement in it to remove it.

main()

{

     int a;

     a = f (10, 3.14) ;

     printf ( " %d ", a );

}

f (int aa, float bb)

{

    return ( ( float ) aa + bb );

}

Answer

Add the following function prototype in main ():


float f ( int, float );

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0 2756
Q:

Two main measures for the efficiency of an algorithm are

A) Time and Space B) Complexity and Memory
C) Data and Space D) Memory and Processor
 
Answer & Explanation Answer: A) Time and Space

Explanation:

Two main measures for the efficiency of an algorithm are Time and Space.

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Q:

Write a c program to create dos command type.

Answer

#include
int main( int count,char * argv[] ) {
    int i;
    FILE *ptr;
    char *str;
    char ch;
    if( count == 1) {


         printf( "The syntax of the command is incorrect.\n" );
    }
    for( i=1;i<cout;i++ ){
         ptr=fopen(argv[i],"r");
         if(ptr==NULL){
             printf("The system cannot find the file specified.");
             if(count>2)
                 printf("\nError occurred while procesing : %s.\n",argv[i]);
         }
         else {
             if(count>2) {
                 printf("%s\n\n",argv[i]);
             }
             while((ch=getc(ptr))!=-1)
                 printf("%c",ch);
         }
         fclose(ptr);
    }
    return 0;
}


 


Save the above file as open.c, compile and execute the go to command mode (current working directory) and write: open xy.c (xy.c any file present in that directory)
To run the open command in all directories and drive you will have to give the path of current working directory in command mode. Write:
C:tc\bin>PATH c:\tc\bin
Now press enter key. Now your open command will work in all directory and drive.

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Q:

Improve the following code using typedef.

struct node

{

      int data1;  float data2;

       struct node *left;

       struct node *right;

};

struct node *ptr;

ptr = (struct node *) malloc (sizeof (struct node) ); 

Answer

typedef struct node * treeptr


typedef struct node


{


         int data1;


         float data2;


         treeptr *left;


         treeptr *right;


}treenode;


treeptr ptr;


ptr = ( treeptr ) malloc ( sizeof ( treenode ) );

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