SafeMath.sol
View Source: contracts/SafeMath.sol
Wrappers over Solidity's arithmetic operations with added overflow checks.
Arithmetic operations in Solidity wrap on overflow. This can easily result
in bugs, because programmers usually assume that an overflow raises an
error, which is the standard behavior in high level programming languages.
SafeMath
restores this intuition by reverting the transaction when anoperation overflows.
Using this library instead of the unchecked operations eliminates an entire
class of bugs, so it's recommended to use it always.
Functions
add(uint256 a, uint256 b)
add(uint256 a, uint256 b, string errorMessage)
sub(uint256 a, uint256 b)
sub(uint256 a, uint256 b, string errorMessage)
mul(uint256 a, uint256 b)
mul(uint256 a, uint256 b, string errorMessage)
div(uint256 a, uint256 b)
div(uint256 a, uint256 b, string errorMessage)
mod(uint256 a, uint256 b)
mod(uint256 a, uint256 b, string errorMessage)
add
Returns the addition of two unsigned integers, reverting on overflow.
Counterpart to Solidity's
+
operator.Requirements:
Addition cannot overflow.
Arguments
add
Returns the addition of two unsigned integers, reverting with custom message on overflow.
Counterpart to Solidity's
+
operator.Requirements:
Addition cannot overflow.
Arguments
sub
Returns the subtraction of two unsigned integers, reverting on underflow (when the result is negative).
Counterpart to Solidity's
-
operator.Requirements:
Subtraction cannot underflow.
Arguments
sub
Returns the subtraction of two unsigned integers, reverting with custom message on underflow (when the result is negative).
Counterpart to Solidity's
-
operator.Requirements:
Subtraction cannot underflow.
Arguments
mul
Returns the multiplication of two unsigned integers, reverting on overflow.
Counterpart to Solidity's
*
operator.Requirements:
Multiplication cannot overflow.
Arguments
mul
Returns the multiplication of two unsigned integers, reverting on overflow.
Counterpart to Solidity's
*
operator.Requirements:
Multiplication cannot overflow.
Arguments
div
Returns the integer division of two unsigned integers. Reverts on division by zero. The result is rounded towards zero.
Counterpart to Solidity's
/
operator. Note: this function uses arevert
opcode (which leaves remaining gas untouched) while Solidityuses an invalid opcode to revert (consuming all remaining gas).
Requirements:
The divisor cannot be zero.
Arguments
div
Returns the integer division of two unsigned integers. Reverts with custom message on division by zero. The result is rounded towards zero.
Counterpart to Solidity's
/
operator. Note: this function uses arevert
opcode (which leaves remaining gas untouched) while Solidityuses an invalid opcode to revert (consuming all remaining gas).
Requirements:
The divisor cannot be zero.
Arguments
mod
Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), Reverts when dividing by zero.
Counterpart to Solidity's
%
operator. This function uses arevert
opcode (which leaves remaining gas untouched) while Solidity uses an
invalid opcode to revert (consuming all remaining gas).
Requirements:
The divisor cannot be zero.
Arguments
mod
Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), Reverts with custom message when dividing by zero.
Counterpart to Solidity's
%
operator. This function uses arevert
opcode (which leaves remaining gas untouched) while Solidity uses an
invalid opcode to revert (consuming all remaining gas).
Requirements:
The divisor cannot be zero.
Arguments
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