Simple C queries

SOME INTERSTING QUERIES IN 'C'
Here are some queries in c.If any comment on any query Pleasemention the query number in your comment.
For answers of these queries watch the 'solutions of c queries' post
The queries will be updated once in a week,so keep in touch with this blog1.
main(){
int i=10;i=i!>40;printf("i=%d",i);
}

2.
#define int charmain(){
int i=65;printf("%d",sizeof(i));
}3.
void main()
{int i=7;printf("%d",i++*i++);
}4.void main()
{char *s="\12345s\n";printf("%d",sizeof(s));
}5.
main()
{int i=-1,j=-1,k=0,l=2,m;m=i++&&j++&&k++l++;printf("%d %d %d %d",i,j,k,l,m);
}6.
main(){
extern int i;i=20;printf("%d",i);
}