Cache length of array when looping

[code423n4]

Handle

0x0x0x

Vulnerability details

Proof of Concept

Example:

for (uint i = 0; i < arr.length; i++) {
//Operations not effecting the length of the array.
}

Loading length of array costs gas. Therefore, the length should be cached, if the length of the array doesn't change inside the loop.
Recommended implementation:

uint length = arr.length;
for (uint i = 0; i < length; i++) {
//Operations not effecting the length of the array.
}

By doing so the length is only loaded once rather than loading it as many times as iterations (Therefore, less gas is spent).

Occurences

./controllers/Controller.sol:453:        for (uint i = 0; i < _strategies.length; i++) {
./converters/GeneralConverter.sol:109:            for (uint8 i = 0; i < tokens.length; i++) {
./converters/GeneralConverter.sol:137:            for (uint8 i = 0; i < tokens.length; i++) {
./converters/GeneralConverter.sol:174:            for (uint8 i = 0; i < tokens.length; i++) {
./converters/GeneralConverter.sol:189:            for (uint8 i = 0; i < tokens.length; i++) {