int64

Int64 is a 64-bit signed integer data type used in many programming languages and platforms. It occupies eight bytes of memory and typically uses two's complement representation, which provides a range that covers negative and positive values. The value range is -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807. An unsigned 64-bit variant exists in most ecosystems, often called UInt64, spanning 0 to 18,446,744,073,709,551,615.

Naming and availability vary by language. In C#, the 64-bit signed integer is System.Int64 and is commonly referred to as long. In Java, the primitive type long is 64-bit signed. In C and C++, long long is typically 64-bit. Go provides int64, Rust provides i64, and SQL dialects use BIGINT for a 64-bit integer.

Int64 values are used for large counts, indices, memory offsets, file sizes, timestamps, and other quantities that may exceed 32-bit limits. They are integral values and support standard arithmetic operations, comparisons, and bitwise operations, subject to the language’s overflow semantics.

Overflow behavior is language-specific: some languages wrap around on overflow, others may throw an exception or require explicit checked arithmetic. When converting from or to other types, care is needed to avoid loss of precision or out-of-range values. Literal ranges and representations can vary by syntax and language, but the underlying concept remains a fixed 64-bit signed integer.

See also: UInt64, i64, BIGINT, long.