Program tracking..

I am unable 2 understand the following programs and their output.. can u pls help..

1.
main()
{
float me=1.1;
double you=1.1;
if (me==you)
printf("I hate C");
else
printf("I love C");
}

2.
main()
{
char word[25];
printf("word\n");
scanf("%[A...I]c",word);
printf("input");
scanf("%[^'0']c",word);
printf("over");
getch();
}

3.
main()
{
char *p="hai friends",*p1;
p1=p;
while(*p!='\0')
++*p++;
printf("%s%s",p,p1);
}

4.
main()
{
int a[]={1,4,3,5,7};
int i=2;
printf("%d",a[i][a]);
getch();
}

These programs are useful for obfuscation contests. Don't write like this. Take #4.

int a[]={1,4,3,5,7};
int i=2;
printf("%d",a[i][a]);

Per my understanding, c evaluates pointer[integer] as
*(pointer+integer)
Addition commutes, (a+b) == (b+a)
*(integer+pointer)
hence you can write
integer[pointer]
But please don't, your fellow programmers aren't likely to think that way.

a[i][a]

a[i] is an integer, giving
integer[a]
a is a pointer
a[i][a] looks valid to me.




#1, I'd have to build and run, otherwise I'd have to spend maybe hours studying IEEE floating point. The key is to investigate number representations and what happens as the compiler casts through successive types. Again, that's part of the c standard.



#3, study precedence and left-to-right versus right-to-left order of operation. Don't write code like that!



#2, study the man pages for printf.