diff options
Diffstat (limited to 'src/uint256.h')
| -rw-r--r-- | src/uint256.h | 29 |
1 files changed, 20 insertions, 9 deletions
diff --git a/src/uint256.h b/src/uint256.h index 8223787041..708f0c2ff1 100644 --- a/src/uint256.h +++ b/src/uint256.h @@ -69,16 +69,27 @@ public: /** @name Hex representation * - * The reverse-byte hex representation is a convenient way to view the blob - * as a number, because it is consistent with the way the base_uint class - * converts blobs to numbers. + * The hex representation used by GetHex(), ToString(), FromHex() and + * SetHexDeprecated() is unusual, since it shows bytes of the base_blob in + * reverse order. For example, a 4-byte blob {0x12, 0x34, 0x56, 0x78} is + * represented as "78563412" instead of the more typical "12345678" + * representation that would be shown in a hex editor or used by typical + * byte-array / hex conversion functions like python's bytes.hex() and + * bytes.fromhex(). + * + * The nice thing about the reverse-byte representation, even though it is + * unusual, is that if a blob contains an arithmetic number in little endian + * format (with least significant bytes first, and most significant bytes + * last), the GetHex() output will match the way the number would normally + * be written in base-16 (with most significant digits first and least + * significant digits last). + * + * This means, for example, that ArithToUint256(num).GetHex() can be used to + * display an arith_uint256 num value as a number, because + * ArithToUint256() converts the number to a blob in little-endian format, + * so the arith_uint256 class doesn't need to have its own number parsing + * and formatting functions. * - * @note base_uint treats the blob as an array of bytes with the numerically - * least significant byte first and the most significant byte last. Because - * numbers are typically written with the most significant digit first and - * the least significant digit last, the reverse hex display of the blob - * corresponds to the same numeric value that base_uint interprets from the - * blob. * @{*/ std::string GetHex() const; /** Unlike FromHex this accepts any invalid input, thus it is fragile and deprecated! |