About four to five days ago I was learning the Bits Manipulation from the Luv Youtube channel .That video was the part of his CP Course and I really appreciated it much. Due to that video I was able to explore the new concepts related to bits and through this blog, I am sharing all of them with you.
1 ) Printing the binary representation of any Number.
void pr_binary(int num){
for(int i=10;i>=0;i--) cout<<((num>>i)&1);
cout<<endl;
}
//Update :You can also represent any number in its binary form as;
cout<<bitset<const_length>(number);
2 ) checking if the ith bit is set or not.
if((a&(1<<i))!=0) cout<<"set"<<endl;
// check if set or not;
else cout<<"Not set"<<endl;
3 ) Counting the number of set bits
int ans=0;
for (int i=31; i>=0;--i)
{
if((a&(1<<i))!=0) ans++;
}
dis(ans);
//Even though the inbuilt function is also there.
cout<<__builtin_popcountll((1ll<<35)-1);
4 ) Some other important operations.
pr_binary(a | (1<<i));
// set that ith bit;
pr_binary(a&(~(1<<i)));
// unset the ith bit;
pr_binary(a ^ (1<<i));
// toggle the ith bit from set to unset and vice-versa;
5 ) For getting the count of odd,even to a number n;
int n,od=0,ev=0;
cin>>n;
for(int i=1;i<=n;i++){
if(i&1) od++;
else ev++;
}
cout<<"Count of Odd"<<od<<endl;
cout<<"Count of Even"<<ev<<endl;
6 ) Dividing or multiplying any number by two
//Although the arithmetic operations are fast ,but by bits manipulation we can make them //more faster.
int n=5;
n=n>>1;
// divide by two
dis(n);
n=n<<1;
// multiply by two
7 ) Some cool operations and playing with Characters
for(char c='A';c<='Z';c++){
cout<<c<<" ";
pr_binary(int(c));
}
for(char c='a';c<='z';c++){
cout<<c<<" ";
pr_binary(int(c));
}
//difference between upper case letter and lower case letter binary is that
//in upper case letter 5th bit!=1;
//in lower case letter 5th bit =1;
cout<<char('A'|(1<<5))<<endl;
//in lower case;
cout<<char('a'&(~(1<<5)))<<endl;
//in upper case;
//actually char of 1<<5 is _(space);
//take any upper case letter and its || with space will get the corresponding lower case letter;
cout<<char('C'|' ')<<endl;
// will make it small c
//take any lower case letter and its || with _(underscore) will get the corresponding upper //case letter;`
cout<<char('c'&'_')<<endl;
// will make it capital C
8 ) Swap with XOR.
int a=4;
int b=5;
a=a^b;
b=b^a;
a=a^b;
// cout<<a<<" "<<b;
9 ) Checking if a number is the power of two.
int n=16;
n&(n-1)?dis("NO"):dis("YES");
//Update : this will not work for n==0;
for n=0;
//we can have the function
bool check_power_of_two(int num){
return n && !(n&(n-1));
}
10 ) For clearing the set bits upto ith bit
int i=4;
//clearing upto 5 the place;
int a=59;
int b=(a&(~((1<<(i+1))-1)));
//clearing the lsb upto ith bit;
pr_binary(b);
i=3;
int c=(a&((1<<(i+1))-1));
//clearing the msb upto ith bit;
pr_binary(c);
Although I have tried my best, but still there can be chance of mistakes .This is my first blog on this platform .Thanks for reading.
