Can Bitwise Operations Be Performed Directly on Floating-Point Numbers in C/C ?

Bitwise Operations on Floating-Point Numbers

Bitwise operations in C/C manipulate the value representation of a number, not its actual value. Floating-point numbers, however, lack a defined bit-level representation in the language.

Compiler Error: & Operand Not Float

Your attempt to perform a bitwise AND (&) operation on a float variable, a, fails because "& operand requires an integer type and cannot be applied to a float. Casting a to an integer, e.g., int a = (int) 1.4123;, allows the operation but performs the bitwise AND on the integer representation of the rounded-off number.

int to void Cast vs float to void Cast

Integers can be cast to void* because they represent values in "raw" memory. Floating-point numbers, on the other hand, do not have a well-defined underlying bit representation. Therefore, they cannot be reliably cast to void*.

Analyzing Floating-Point Bit Content

To analyze the bit content of a floating-point number, you can use a union to merge the float with a representation type that supports bitwise operations:

union {
  float f_value;
  unsigned int u_value;
} number;

number.f_value = 1.4123;
unsigned int bitmask = (1 << 3);
number.u_value &= bitmask; // Perform bitwise AND on the integer representation

Alternatively, in C , you can reinterpret the floating-point object as an array of unsigned characters:

float f = 5.0;
unsigned char *c = reinterpret_cast<unsigned char *>(&f);
// Inspect bit content from c[0] to c[sizeof(f) - 1]

Conclusion

Bitwise operations cannot be directly performed on floating-point numbers because they do not have a defined bit-level representation. Instead, you can analyze the bit content of the underlying memory using methods such as unions or reinterpretation.

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