1.) **__builtin_popcount(x)**: Counts the number of one’s(set bits) in an integer(long/long long).

Ex- int x=5;
    cout<<**__builtin_popcount(x)**<<endl;   //returns 2.

If x is of long type,we can use **__builtin_popcountl(x)** If x is of long long type,we can use **__builtin_popcountll(x)**

2.) **__builtin_parity(x)**: Checks the Parity of a number.Returns true(1) if the number has odd parity(odd number of set bits) else it returns false(0) for even parity(even number of set bits).

Ex- int x=5;
    cout<<**__builtin_parity(x)**<<endl;   //returns 0.

If x is of long type,we can use **__builtin_parityl(x)** If x is of long long type,we can use **__builtin_parityll(x)**

3.) **__builtin_clz(x)**: Counts the leading number of zeros of the integer(long/long long).

If x is of long type,we can use **__builtin_clzl(x)** If x is of long long type,we can use **__builtin_clzll(x)**

Ex- int x=16;       // 00000000 00000000 00000000 00010000 (32 bits)
      cout<<**__builtin_clz(x)**<<endl;   //returns 27.

  Ex- long x=16;       // 00000000 00000000 00000000 00010000 (32 bits)
      cout<<**__builtin_clzl(x)**<<endl;   //returns 27.

  Ex- long long x=16;       // 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00010000 (64 bits)
      cout<<**__builtin_clzll(x)**<<endl;   //returns 59.

4.) **__builtin_ctz(x)**: Counts the trailing number of zeros of the integer(long/long long).

If x is of long type,we can use **__builtin_ctzl(x)** If x is of long long type,we can use **__builtin_ctzll(x)**

Ex- int x=16;       // 00000000 00000000 00000000 00010000 (32 bits)
    cout<<**__builtin_ctz(x)**<<endl;   //returns 4.

In case of both **__builtin_ctzl(x)** and **__builtin_ctzll(x)**,the answer is same.