I am using a uint128_t as an id type for a contract I am working on. For a certain check, I need to convert this variable to a string so I can check for it in another table (whose type cannot be changed). How can I convert the uint128_t variable to a string without having to#include "sstream", which is warned against by the compiler?

1 Answer 1


I don't know if this is the best solution but I used a little parser, which is closely connected to the eosio account name conversion from GitHub:

static const char* charmap = "0123456789";

std::string uint128ToString(const uint128_t& value)
    std::string result;
    result.reserve( 40 ); // max. 40 digits possible ( uint64_t has 20) 
    uint128_t helper = value;

    do {
        result += charmap[ helper % 10 ];
        helper /= 10;
    } while ( helper );
    std::reverse( result.begin(), result.end() );
    return result;

It will divide by 10 and use the charmap to identify the number representation to use.

  • This was the approach I ended up taking. It seems to work well. Nov 13, 2018 at 21:56

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