Programming Questions

extern int i is a declaration and not a definition, hence Error occured.

 #include<stdio.h>
int main(){
  int r,i,j,k;
  printf("Enter the number range: ");
  scanf("%d",&r);
  for(i=1;i<=r;i++){
      for(j=1;j<=10;j++)
           printf("%d*%d=%d ",i,j,i*j);
      printf("\n");
  }
  return 0;
}

Sample Output:
Enter the number range: 5

1*1=1 1*2=2 1*3=3 1*4=4 1*5=5 1*6=6 1*7=7 1*8=8 1*9=9 1*10=10
2*1=2 2*2=4 2*3=6 2*4=8 2*5=10 2*6=12 2*7=14 2*8=16 2*9=18 2*10=20
3*1=3 3*2=6 3*3=9 3*4=12 3*5=15 3*6=18 3*7=21 3*8=24 3*9=27 3*10=30
4*1=4 4*2=8 4*3=12 4*4=16 4*5=20 4*6=24 4*7=28 4*8=32 4*9=36 4*10=40
5*1=5 5*2=10 5*3=15 5*4=20 5*5=25 5*6=30 5*7=35 5*8=40 5*9=45 5*10=50

0  0  1

That's what some of the compilers would give. But some other compiler may give a different answer. The reason is, when a single expression causes the same object to be modified and then inspected the behaviour is undefined.

Here we are initalising the function pointer p to the address of the function fun(). But during this initialisation the function has not been defined. Hence an error.

To eliminate this error add the prototype of the fun() before declaration of p, as shown below:

extern int fun();    or simply  int fun();

In spite of defining the function f() as returning void, the program is trying to collect the value returned by f() in the variable a.

Yes

1004  2  2

main()

{

   char *str[] = { "Frogs", "Do", "Not", "Die." , "They", "Croak!" };

   int i;

         for ( i = 0;i<=5;i++)

         printf ("\n%s%d", str[i], strlen( str[i]));

}