ygcool / solidity-standard-library

Solidity standard library (Array, random, math, string)

Quick overview of the library

Array.sol

Storage array wrapper.

UintArray contract members:

• UintArray(uint[] data) - construct new array contract
• min() - returns minimal array element
• max() - returns maximal array element
• sum() - returns sum of all array elements
• set(uint[] arr) - assign array
• get() - returns stored array
• sort() - sorts all array elements

IntArray contract members:

• IntArray(int[] data) - construct new array contract
• min() - returns minimal array element
• max() - returns maximal array element
• sum() - returns sum of all array elements
• set(int[] arr) - assign array
• get() - returns stored array
• sort() - sorts all array elements

Convert.sol

Helper contract to convert strings or ints/uints.

Converter contract members:

• toString(uint x) - converts uint to string
• toUint(string str) - converts string to uint

Math.sol

Basic mathematical functions.

Math contract members:

• sqrt(uint x) - computes square root of x
• mexp(uint x, uint k, uint m) - computes (pow(x, k)) mod m

Memory.sol

WARNING: These functions are used to perform low-level memory access and may cause security risk when used improperly.

STDMemory contract members:

• m_ref_uint(uint[] arr) - returns address of arr
• m_unref_uint(uint ptr) - returns array pointed by ptr
• m_ref_int(int[] arr) - returns address of arr
• m_unref_int(uint ptr) - returns array pointed by ptr

Multiprecision.sol

Floating point calculations. Note: double_t(1, 5) will be 1.05 but double_t(1, 50) will be 1.5 with dscale = 2 (Number of digits after dot)

Example:

   import "multiprecision.sol";
   contract Test is Double
   {
       function test() internal
       {
           double memory a = double_t(1, 20); // 1.20
           double memory b = double_t(0, 2); // 0.02
           double memory result = double_add(a, b); // 1.22
           
           a = double_t(2, 0); // 2.00
           b = double_t(1, 0); // 1.00
           a.sign = true; // -2.00
           result = double_add(a, b); // -2.00 + 1.00 = -1.00
           
           result = double_sub(a, b); // -2.00 - 1.00 = -3.00
           result = double_mult(a, b); // -2.00 * 1.00 = -2.00
           result = double_div(a, b); // -2.00 / 1.00 = -2.00
           
           dscale = 3; // change precision (.00 -> .000)
           double_t(1, 5); // now 1.005
           double_t(1, 50); // now 1.050
           double_t(1, 500); // now 1.500
       }
  }

Double contract members:

• struct double - signed double representation
• double_t(int integral, uint fractional) - creates a new double as integral.fractional
• double_add(double a, double b) - a + b
• double_sub(double a, double b) - a - b
• double_mult(double a, double b) - a×b
• double_div(double a, double b) - a / b
• double_lt(double a, double b) - a < b
• double_le(double a, double b) - a <= b
• double_eq(double a, double b) - a == b
• double_ge(double a, double b) - a >= b
• double_gt(double a, double b) - a > b

Random.sol

Random number generator based on SHA3 function (not cryptographicaly secure)

Random contract members

• rand(uint seed) - returns random unsigned int generated wuth seed
• randint() - returns random unsigned int
• randbytes(uint size, uint seed) - returns array of random bytes