Bit fields

[mehak]

the following code compiles however the c version of it gives a compilation error

C:\Users\Mehak\Desktop\prac\Untitled2.c||In function 'main':|
C:\Users\Mehak\Desktop\prac\Untitled2.c|7|error: width of 'i' exceeds its type|
||=== Build finished: 1 errors, 0 warnings (0 minutes, 0 seconds) ===|

is thereany limit on the number of bits used in bit fields?

#include<iostream>
using namespace std;
int main()
{
    struct bits
    {
        int i:40;
    }bit;

    cout<< sizeof(bit);
    return 0;
}

[Lowest0ne]

You're asking for 40 bits of an int, which is probably only 32 bits.

C++ has a bitset already:
http://www.cplusplus.com/reference/bitset/bitset/?kw=bitset

[Cubbi]

the following code compiles however the c version of it gives a compilation error

C and C++ are different languages, that should not be a surprise.

is there any limit on the number of bits used in bit fields?

There is no limit on the number of bits in C++, but there is a limit on the maximum value that is stored in the bit field.

To quote http://en.cppreference.com/w/cpp/language/bit_field

std::uint8_t b : 1000; would still hold values between 0 and 255. the extra bits become unused padding.

(in C, as you've seen, the limit on the number of bits is the width of the underlying type)

And yes, use std::bitset