Parsing & formatting

BigInteger

• Default parsing is base 10.
• BigInteger(str, base) supports base 2..62 (and 0 for GMP auto).
• toString(base) uses the same base rules.

BigDecimal

• Accepts:
• optional sign
• fractional part .
• exponent e / E
• underscores _ as separators (removed before parsing)
• Parsing rounds to the instance scale using HalfEven.

Examples:

BigDecimal a("1.234567", 4);      // rounds to 1.2346 (HalfEven)
BigDecimal b("1.23445", 4);       // ties to even -> 1.2344
BigDecimal c("12e-3", 6);         // 0.012000

BigFloat

• Uses GMP mpf_set_str(..., base=10).
• Output:
• toStringScientific() for stable representation
• toStringFixed(digits) for fixed digits