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# bitset all() function in C++ STL

• Last Updated : 18 Jun, 2018

The bitset::all() is a built-in function in C++ STL which returns True if all bits are set in the binary representation of a number if it is initialized in the bitset. It returns False if all the bits are not set.

Syntax:

```bool bitset_name.all()
```

Parameter: This function does not accepts any parameter.

Return Value: The function returns a boolean value. The boolean value returned is true if all the bits are set, else the returned value is false,

Below programs illustrates the bitset::all() function.

Program 1:

 `// CPP program to illustrate the``// bitset::all() function``#include ``using` `namespace` `std;`` ` `int` `main()``{``    ``// Initialization of bitset``    ``bitset<4> b1(string(``"1100"``));``    ``bitset<6> b2(string(``"111111"``));`` ` `    ``// Function that checks if all``    ``// the bits are set or not``    ``bool` `result1 = b1.all();``    ``if` `(result1)``        ``cout << b1 << ``" has all bits set"``             ``<< endl;``    ``else``        ``cout << b1 << ``" does not have all bits set"``             ``<< endl;`` ` `    ``// Function that checks if all``    ``// the bits are set or not``    ``bool` `result2 = b2.all();``    ``if` `(result2)``        ``cout << b2 << ``" has all bits set"``             ``<< endl;``    ``else``        ``cout << b2 << ``" does not have all bits set"``             ``<< endl;`` ` `    ``return` `0;``}`
Output:
```1100 does not have all bits set
111111 has all bits set
```

Program 2:

 `// CPP program to illustrate the``// bitset::all() function``// when the input is as a number`` ` `#include ``using` `namespace` `std;`` ` `int` `main()``{``    ``// Initialization of bitset``    ``bitset<2> b1(3);``    ``bitset<3> b2(5);`` ` `    ``// Function that checks if all``    ``// the bits are set or not``    ``bool` `result1 = b1.all();``    ``if` `(result1)``        ``cout << b1 << ``" has all bits set"``             ``<< endl;``    ``else``        ``cout << b1 << ``" does not have all bits set"``             ``<< endl;`` ` `    ``// Function that checks if all``    ``// the bits are set or not``    ``bool` `result2 = b2.all();``    ``if` `(result2)``        ``cout << b2 << ``" has all bits set"``             ``<< endl;``    ``else``        ``cout << b2 << ``" does not have all bits set"``             ``<< endl;`` ` `    ``return` `0;``}`
Output:
```11 has all bits set
101 does not have all bits set
```
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