Optimizations to the Unoptimized.sol contract

Optimized.sol

pragma solidity ^0.4.0;

contract Optimized {
    
    bool oftenTrue = true;
    bool oftenFalse = false;
    
    uint loops = 0;
    
    bytes32 constant statictext = "Hello world";
    
    // Remove unnecessary code
    // reduces costs of deploying the contract
    
    function p1(uint x) public pure returns(bool) {
        if(x > 5)
            return true;
    }
    
    // Reduce expensive operations
    
    // Take advantage of short circuiting rules
    
    function shortCircuit() public view returns(bool){
        if(oftenTrue || oftenFalse){    //The operators || and && apply the common short-circuiting rules. 
            return true;                //This means that in the expression f(x) || g(y), if f(x) evaluates 
        }                               //to true, g(y) will not be evaluated even if it may have side-effects.
    }
    
    function shortCircuit2() public view returns(bool){
        if(oftenFalse && oftenTrue){    // In the AND conditional, if the first condition evaluates
            return false;               // to false, the second condition is not evalutated, saving gas.
        } else {                        // Put the conidtion that is more likely to be false first in the   
            return true;                // conidtion check
        }
    }   
    
    // Remove expensive operations from the loop
    function looping(uint x) public returns (bool){
        uint total = 0;
        for(uint i; i < x; i++){
            total += 1;
        }
        loops += total;             // only reads and writes to storage 1 time
        return true;
    }
    
    // Hint: Reduce number of loops
    function looping2(uint x) public pure returns(bool){
        uint m = 0;
        uint v = 0;
        for(uint i = 0; i < x; i++){
            m += i;
            v -= i;
        }
        return true;
    } 
    
    // Hint: Minimal code in a loop
    function looping3(uint x, uint y) public pure returns(uint){
        if (x <= 0) return y;           // The x check does not need to be in the 
        for(int i = 0; i < 100; i++){   // loop. Save gas by putting outside
            y += x;                     
        }
        return y;
    }    
    
    // Use of fixed size byte arrays
    
    function bytesArray() public view returns(uint){
        bytes bytesArray;       // Using type bytes instead of type byte[] is more efficient
        return gasleft();
    }
    
    
    function getString() public pure returns(bytes32){
        return statictext;      // statictext is now type bytes32 rather than string
    }
    
}