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Programming-Idioms

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Idiom #345 Convert string to big integer

Create the integer value i initialized from its string representation s (in radix 10)

Use an integer type that can hold huge values. Explain what happens if s cannot be parsed.

i = int(s)

The type int is unbounded

This raises an exception if s is invalid
i = s.to_i

Extraneous characters past the end of a valid number are ignored. If there is not a valid number at the start of s, 0 is returned. This never raises an exception.
import "math/big"
i := new(big.Int)
_, ok := i.SetString(s, 10)

If s cannot be parsed, then ok will be false
New implementation...
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programming-idioms.org 
i = int(s)
i = s.to_i
i := new(big.Int)
_, ok := i.SetString(s, 10)
BigInteger i = new BigInteger(s, 10);
i := s;