Strings library (#1746)

* Feature Issue #1745 * Feature Issue #1745 remove whitespace in contract * Feature Issue #1745 fix Solidity linter issues * Feature Issue #1745 fix JS lint issues * Update contracts/drafts/Strings.sol Co-Authored-By: Nicolás Venturo <nicolas.venturo@gmail.com> * Update contracts/drafts/Strings.sol Co-Authored-By: Nicolás Venturo <nicolas.venturo@gmail.com> * Update contracts/drafts/Strings.sol Co-Authored-By: Nicolás Venturo <nicolas.venturo@gmail.com> * Updates based on PR feedback * Remove trailing whitespace * Update tests based on @nventuro feedback * Removed return name * Rename length as suggested * Rename temp variables in uint256ToString * Renamed bytes variable to buffer * Change concatenate to use abi.encodePacked * Moved OraclizeAPI reference to unit256ToString * Add emoji concat test * Remove concatenate * Remove concatenate from StringsMock and test * Rename function to fromUint256 * Update StringsMock.sol
2019-05-28 02:31:09 +10:00
parent a83f680a63
commit fbbff53528
3 changed files with 70 additions and 0 deletions
--- a/contracts/drafts/Strings.sol
+++ b/contracts/drafts/Strings.sol
@ -0,0 +1,38 @@
+pragma solidity ^0.5.0;
+
+/**
+ * @title Strings
+ * @dev String operations.
+ */
+library Strings {
+    /**
+     * Concatenates two strings.
+     * string(abi.encodePacked(a, b))
+     * https://solidity.readthedocs.io/en/latest/types.html?highlight=concatenate
+     */
+
+    /**
+     * @dev Converts a uint256 to a string.
+     * via OraclizeAPI - MIT licence
+     * https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
+     */
+    function fromUint256(uint256 value) internal pure returns (string memory) {
+        if (value == 0) {
+            return "0";
+        }
+        uint256 temp = value;
+        uint256 digits;
+        while (temp != 0) {
+            digits++;
+            temp /= 10;
+        }
+        bytes memory buffer = new bytes(digits);
+        uint256 index = digits - 1;
+        temp = value;
+        while (temp != 0) {
+            buffer[index--] = byte(uint8(48 + temp % 10));
+            temp /= 10;
+        }
+        return string(buffer);
+    }
+}