Julia’s BigInt type represents integers of arbitrary size, making it useful when fixed-width types such as Int128 cannot hold a value. Julia does not automatically widen overflowing integer operations, so BigInt is an explicit choice rather than an automatic fallback. section 2.3
Create a big integer with BigInt(42), or use the big"42" literal. The literal is parsed into a BigInt when the program is parsed, avoiding repeated conversion during execution. section 11.4.4 section 11.4
Choosing BigInt for a large value
Use BigInt when a fixed-width integer is not sufficient: n = BigInt(42). For repeated creation of the same constant, prefer big"42" so Julia creates the big integer during parsing rather than converting it each time the code runs. section 2.3 section 11.4.4
Keep these practical trade-offs in mind:
- Choose BigInt only when necessary: its flexibility costs more memory and lower performance. section 2.3
- Use BigInt explicitly because Julia does not automatically promote an overflowing fixed-width arithmetic result to a larger integer type. section 2.3
- Treat big"..." as a specialized literal form rather than an ordinary string conversion. section 11.4.4
