C Datatype Questions

 1.void main(){

   int i=320;

   char *ptr=(char *)&i;

   printf("%d",*ptr);

}

As we know size of int data type is two byte while char pointer can pointer one byte at time.

Memory representation of int i=320

So char pointer ptr is pointing to only first byte as shown above figure.

*ptr i.e. content of first byte is 01000000 and its decimal value is 64.

2.void main(){

char c=125;

    c=c+10;

    printf("%d",c);

}

As we know char data type shows cyclic properties i.e. if you will increase or decrease the char variables beyond its maximum or minimum value respectively it will repeat same value according to following cyclic order:

So,

125+1= 126

125+2= 127

125+3=-128

125+4=-127

125+5=-126

125+6=-125

125+7=-124

125+8=-123

125+9=-122

125+10=-121

3.

void main(){

   float a=5.2;

  if(a==5.2)

     printf("Equal");

  else if(a<5.2)

     printf("Less than");

  else

     printf("Greater than");

}

5.2 is double constant in c. In c size of double data is 8 byte while a is float variable. Size of float variable is 4 byte.

So double constant 5.2 is stored in memory as:

101.00 11001100 11001100 11001100 11001100 11001100 11001101

Content of variable a will store in the memory as:

101.00110 01100110 01100110

It is clear variable a is less than double constant 5.2

Since 5.2 is recurring float number so it different for float and double. Number likes 4.5, 3.25, 5.0 will store same values in float and double data type.

Note: In memory float and double data is stored in completely different way

3.

void main(){

char c='\08';

printf("%d",c);

}

In c any character is starting with character ‘\’ represents octal number in character. As we know octal digits are: 0, 1, 2, 3, 4, 5, 6, and 7. So 8 is not an octal digit. Hence ‘\08’ is invalid octal character constant.

Reference Links:

http://cquestionbank.blogspot.in/2012/02/data-type-questions-in-c.html