5. What is an lvalue?

Ans:
An lvalue is an expression to which a value can be assigned. The lvalue expression is located on the left side of an assignment statement, whereas an rvalue is located on the right side of an assignment statement. Each assignment statement must have an lvalue and an rvalue. The lvalue expression must reference a storable variable in memory. It cannot be a constant.

Ex - 1:What is the output?

main()
{
unsigned int i=10;
while(i-- >= 0)
printf("%u ",i);

}

Ans:
10 9 8 7 6 5 4 3 2 1 0 65535 65534…..

Explanation:
Since i is an unsigned integer it can never become negative. So the expression i-- >=0 will always be true, leading to an infinite loop.

Ex - 2: What is the output?
#include
main()
{
int x,y=2,z,a;
if(x=y%2) z=2;
a=2;
printf("%d %d ",z,x);
}

Ans:
Garbage-value 0

Explanation:
The value of y%2 is 0. This value is assigned to x. The condition reduces to if (x) or in other words if(0) and so z goes uninitialized.
Thumb Rule: Check all control paths to write bug free code.

Ex - 3: What is the output?

main()
{
unsigned int i=65000;
while(i++!=0);
printf("%d",i);
}

Ans:
1

Explanation:
Note the semicolon after the while statement. When the value of i becomes 0 it comes out of while loop. Due to post-increment on i the value of i while printing is 1.