quick guide

1.what will be the output of the following program
main()
{
int a[5], i;
static int b[5];
for(i=0 ; i<5 ;i++)
print f(%d %d %d , i, a[i], b[i]);
}

output: 0 100 0
1 -75 0
2 123 0
3 1245 0
4 347 0

Explanation :since the storage class of the array a[] has
not been mentioned, the default storage class auto is
assigned for it. As against this, the storage class of b[]
has been explicitly mentioned as static. The default value
of auto storage class variable is any garbage value and the
default value of static storage variable is 0. therefore all
zeros are printed out for b[], where as garbage values are
printed out for a[].

2.
main()
{
static int sub[5] = {10,20,30,40,50};
int i;
for (i=0;i<=4;i++)
{
if(i<=4)
{
sub[i]=i*i;
print f( %d, sub[i]);
}
}
}

output: no output

Explanation:there is a semicolon at the end of the for loop,
thus the loop is reduced to the form:
for(i=0;i<=4;i++)
this loop repeats the null statement (;)5times and then the
control comes out of the loop. At this time the value of i
has become 5 and hence the if condition fails and the
control reaches the closing brace of main(). The execution
is therefore terminated without any output to the screen.

3.
int b[5];
main()
{
static int a[5];
int i;
for(i=0;i<=4;i++)
print f(%d %d, b[i], a[i]);
}

output : 0 0
0 0
0 0
0 0
0 0

Explanation: default initial value of a static or extern
storage class variable is 0. thus ,though the array b[] and
a[] have not been initialized, the fact that their storage
class is extern and static respectively causes their values to
be 0.