/ˌjuːˌaɪˈɛnˈtiːˈsɪksˈtɪi/
noun … “Unsigned 64-bit integer.”
UINT64 is a fixed-size integer data type representing non-negative whole numbers ranging from 0 to 18,446,744,073,709,551,615 (264 − 1). Being unsigned, UINT64 does not support negative values. It is widely used in systems programming, cryptography, file offsets, and any context requiring precise, large integer representation. UINT64 is typically implemented in memory as 8 bytes, conforming to the platform's endian format.
Key characteristics of UINT64 include:
- Fixed-width: always occupies 8 bytes, ensuring predictable storage and arithmetic overflow behavior.
- Unsigned: represents only non-negative integers, doubling the maximum positive value compared to a signed 64-bit integer.
- Efficient arithmetic: hardware-level operations support addition, subtraction, multiplication, and bitwise operations.
- Cross-platform consistency: guarantees the same numeric range and storage size across compliant architectures.
- Interoperability: used in CPU registers, memory addressing, and API data contracts requiring 64-bit values.
Workflow example: In C++:
#include <iostream>
#include <cstdint>
int main() {
std::uint64_t value = 18446744073709551615ULL
std::cout << "UINT64 value: " << value << std::endl
return 0
}This example declares a UINT64 variable using std::uint64_t, assigns the maximum possible value, and prints it. Overflow occurs if a computation exceeds 264 − 1, wrapping around modulo 264.
Conceptually, UINT64 is like a set of 64 light switches, each representing a binary digit. By flipping these switches on or off, you can represent any number from 0 to 264 − 1, allowing precise and large numeric representation.