Questions tagged [require]

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Functions with boolean return type while using require()

I am trying to understand the reasoning for this: (for an online class) mapping (uint => uint) public multiplier; /** * Called by the owner of the TollBoothOperator. * Can be used to update a ...
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1answer
696 views

Remix Warning : Assert

I am trying to compile a contract on remix and have run into the following warning : Use assert(x) if you never ever want x to be false, not in any circumstance (apart from a bug in your code). ...
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4answers
3k views

Unit testing for assert()/require() in Truffle/Solidity

If I write a function like so: function calculate(int x) public returns (int) { require(x > 0); // Do other stuff return x; } How would I write a JavaScript unit test in Truffle ...
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1answer
2k views

Solidity multiple vs single require

One of the functions of my smart contract can only be executed if three conditions are met. At the moment I have a single require which combines all the conditions like this: require(evalCond1() &...
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1answer
173 views

How to add requirements to the token contract: 1) owner has enough tokens and 2) minimum sum of ETH of the receivers before updating balances

Could you check if these lines are correct and will work? In this code I have two requirements: I want to check if the owner has enough tokens (10 millions tokens) before updating balances and also ...
1
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0answers
269 views

Catch a “require()” in frontend

I was trying to validate a transaction with some conditions on contract level and was wondering if it was possible in any way to give user feedback in the frontend if a require() fails - aka if it ...
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3answers
202 views

Require: How to avoid users of my smart contract from losing their ether

I have a smart contract lottery that requires people to send exactly 0.2 ethers to its address in order to participate. In the constructor: ante = 0.2 ether; And in the payable function ...
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1answer
297 views

Control structure with truffle (assert and require)

When I'm trying to deploy contracts that contain assert and require using truffle I receive Error: Undeclared identifier. e.g: pragma solidity ^0.4.8; contract Owned{ address public owner = ...

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