Questions tagged [string]

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TypeError: Type function (uint256) pure returns (string memory) is not implicitly convertible to expected type string memory

In Remix I'm getting this strange error while calling Strings.sol library: TypeError: Type function (uint256) pure returns (string memory) is not implicitly convertible to expected type string memory. ...
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29 views

solidity convertion uint256 and address to string

Is there a way to easily convert uint256 and address types to string so that we can get a human readable value?
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11 views

Invalid string crashes Remix IDE

If I have an empty function that accepts a string memory input, and if I pass invalid strings like: " "a """ the Remix IDE crashes. Is this just an issue with Remix? If not, ...
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14 views

Any known hacks by storing string with non-alphanumeric values?

I was checking out hashmasks smart contracts, and they have the following rules for names: No name can be identical There is a limit of 25 symbols (including spaces) Uniqueness is case insensitive (i....
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17 views

Solidity: How to represent bytes32 as string

This may be simple in other languages but I can't figure out how to do it in Solidity. I have a bytes32 like this 0x05416460deb76d57af601be17e777b93592d8d4d4a4096c57876a91c84f4a712. I don't want to ...
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25 views

Concatenating strings overwriting a variable

I'm building a SC with many strings and concatenations. Is there any way to overwrite a string and, moreover, not using an auxiliary method? Something like: // SPDX-License-Identifier: MIT pragma ...
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1answer
29 views

How to concatenate an address to a string in solidity

I am trying to find the correct way to concatenate an Ethereum address to a string in Solidity v0.6.7 I tried the following but it did not seem to work : function append(string a, address b) ...
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6 views

Check string similarity percentage

How can I efficiently check the similarity of two strings? Or better yet, if I have an array of strings, I want to check that the given string is less than e.g. 80 % similar to any of the other ...
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36 views

VM error: invalid opcode. invalid opcode The execution might have thrown

I am trying to take in a 512 character long string and extract the first 312 characters from the string. This is my test on a small scale, tryign to extract 12 characters out from a 30 character long ...
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2answers
19 views

How to ensure that a string parameter to a function is not empty?

Lets say that I have a function which needs two string parameter , function data(string memory _firstname, string memory _lastname) public { buyer[msg.sender] = Buyer(_firstname, _lastname); } Now, I ...
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2answers
92 views

how to set a require for a string to not be null

I want to write a require condition for string that string variable could not be null. How to write because string is not taking the != operator function createOrder(address _seller, string memory ...
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1answer
195 views

Can I use an emoji as part of a string in Solidity?

Can I use an emoji in Solidity?
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0answers
26 views

String to float maintaining decimal places

I've seen some thread already however I haven't found anywhere a way of converting a string number to float number and maintaining the decimals. ie "27.546" to 27.546
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11 views

How can I generate hash of string received from function argument

I want to generate hash of string received through function argument. Sha256 require bytes in argument. How can I convert and then save hash in _hash variable. struct ORGANIZATION{ bytes32 hash; ...
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1answer
222 views

In solidity, how to copy a string or pass it by value?

In this example I only modify string a, but both a and b are changed. It seems like the string wasn't copied. I only want to change a. How do you copy a string and how do you pass a string by value to ...
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1answer
195 views

What is the maximum size of string which we can store on solidity?

Is there a limit to the size of a string that we can store on the Ethereum blockchain?
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19 views

How much is the biggest BytesX type in solidity? (Bytes32?)

I'm trying to keep it simple while returning and array of strings. I want to return a fixed bytesX array with small text. How much is the possible X in the BytesX type? In Remix it seems to be Bytes32....
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1answer
218 views

Calling a string variable

Update2: Ismael highlighted that upgrading drizzle and Web3 were crucial. I was using drizzle 1.3 and Web3 1.0. So, using the same Solidity code, I can now read a string array into a webpage, using ...
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1answer
58 views

How do I order strings in Solidity?

I'm a newbie to smart contract development, and I'm looking to order strings using solidity, I don't care that much what kind of ordering method (alphabetical for example) is used, I just want it to ...
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115 views

join an array of strings and map, filter, reduce functions in solidity

I want to concatenate an array of strings into a single string using solidity, just like the array join function in javascript and python. Also I want to do map/filter/reduce functions in an array. Is ...
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2answers
714 views

Solidity Split Comma-Delimited String into Individual words

Since Solidity functions can't accept String Arrays as arguments, I'm trying instead to pass in a long comma-delimited string, and then convert it to an array of strings on the fly. I'm close - but ...
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1answer
305 views

How to concatenate uint to address in solidity?

I would like to concatenate an Ethereum address to an uint in Solidity. How can I do that?
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1answer
112 views

TypeError: Type string calldata slice is not implicitly convertible to expected type string memory

I want to slice a string and save it to a memory or storage variable. Is this possible? function test(string calldata _input) external{ string memory something = _input[1:3]; } I am ...
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0answers
23 views

Making sure a string (input/output) is less then 64 characters

I'm working though some basic solidity tutorials using remix. I'm having trouble with the concept that there is no way to edit a string built into the language. In other programing languages I would ...
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40 views

Splice an Address

So in javascript I can take a string such as yourString[7] and get the 8th character within that string returned to me in string format. I want to take the last character in an Ethereum address, be an ...
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0answers
25 views

Compare strings

I want to compare two strings but, by using: require(keccak256(abi.encodePacked(_car))==keccak256(abi.encodePacked(car))); I get the following error: InternalCompilerError: Unknown ...
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1answer
156 views

Convert a string in scientific notation to a number

my smart contract uses an Oracle to retrieve the price. The price is returned as a string in scientific notation, for example, "3e-8". How I can convert this to number (uint)? The token has ...
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0answers
28 views

Passing a hash value to function

I'm trying to authenticate users by comparing the hashes created by backend server and contract. Seems like "byte32" values cannot be coerced into strings. So, instead I'm converting it into ...
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1answer
179 views

Explicit type conversion not allowed from “string memory” to “uint256”

I'm using an oracle to get results from a custom api. The result is in string by default. I want to convert it to uint256, so that I can perform basic arithmetic functions. Here's my code: function ...
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1answer
80 views

In Solidity, Is there any situation, when string is necessary?

In Solidity, Is there any situation, when string is necessary? Please can u explain when I should use string instead of bytes or bytesN? Thanks!
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0answers
301 views

How can I return string array in solidity?

This is my struct: struct Token { address tokenAddress; uint256 minAmount; bool emergencyUnlock; TokenStatus status; string name; uint256 decimal; string thumbnailUrl; } ...
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0answers
60 views

Gas-efficient string concatenation

My use-case requires that I feed my contract with a long string (Base64 data), which requires to split it and send it over several transactions so as to not reach gas limit. Then the contract rebuilds ...
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1answer
61 views

Read and write private variable from child contract

I have a contract MyContract is ERC721. MyContract needs to concatenate a string with an existing token URI using this function: string(abi.encodePacked(_tokenURIs[_tokenId], _URI)); Problem is all ...
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1answer
27 views

How to save long textual data on blockchain? [closed]

I need to write blogs and save them on blockchain. What are efficient possibilities to store such data on blockchain? Thanks for reading the question, already appreciate your time.
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1answer
45 views

Where does the length parameter end and the actual string start in an abi encoded string?

Assuming I decided to ABI encode a very long string (for the purpose of this question I just picked an arbitrary 5-paragraph lorem ipsum text generate by https://www.lipsum.com/feed/html) and get out ...
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1answer
36 views

Why does declaring returns type bytes memory give a compiler error?

If we have the following code: pragma solidity >= 0.5; contract stringsContract { function takesTwo(string memory str, uint idx) public pure returns (bytes memory) { bytes memory ...
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1answer
59 views

Garbage in string parameters of events

I have an event defined like this: event Created( address indexed target, string indexed name ); I do emit Created(..., _name); // called function with _name = "comment" which gives ...
1
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1answer
392 views

Bytes memory as a function parameter increase gas cost

I've a smartcontract compiled with pragma solidity ^0.4.0; version and one function receives a bytes parameters which contain a long string. In these version it doesnt need to set the parameters as "...
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1answer
263 views

Solidity. Concatenate and hash two strings

Hi all I need tho sha256 two strings. I am new to solidity. This is what I've got: function addressToString(address _addr) public pure returns(string memory) { bytes32 value = bytes32(uint256(...
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1answer
37 views

Solidity. Concatenate hash w address. TypeError: Operator + not compatible with types string memory and address payable

I am trying to do something simple: examsFinalHash = keccak256(examHash + msg.sender); but I get the following error: TypeError: Operator + not compatible with types string memory and address ...
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1answer
312 views

What's the proper way to store a long string (like a news article) in Solidity?

I'm working on Layer 2 so gas/efficiency aren't primary concerns, assuming the function can be executed by the EVM
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1answer
77 views

Storing a monero address in smart contracts?

Assuming I would have to store Monero addresses or any cryptonote based coins addresses in a smart contract, would there be any issues? Consider that those addresses are as long as this random ...
1
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1answer
150 views

How to verify the sha256 result of integer 5 in the Zokrates tutorial?

The Zokrates tutorial here starts with calculating the SHA256 hash of (the number) 5. The hex representation of the result is shown at the bottom here: However, I could not reproduce this on my ...
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1answer
63 views

library modifying string vs string literal

I have a library which has the following function: function strConcat( string memory _a, string memory _b ) internal pure returns (string memory) My contract implements the library ...
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2answers
204 views

How to convert string to bytes256 or arbitrary bytes?

I already know how to convert bytes32ToString and stringToBytes32: function bytes32ToString(bytes32 x) public pure returns (string memory) { bytes memory ...
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1answer
35 views

Can I use string(or any type) list as an argument of an event?

It`s my event. event Transfer(address sender, address receiver, string[] denoms, uint256[] amounts); And I view an Transfer event with watch() function, It`s the result. { address: "...
2
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1answer
359 views

Solidity: How to replace specific string position with letter?

I would like to replace a letter at a specific position of a string with another letter. function _stringReplace(string memory _string, uint256 _pos, string memory _letter) internal pure returns (...
1
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1answer
161 views

Assert.equals() weird behavior does not recognize (apparently) equal strings

I'm facing problems related to string comparison using Assert.equals() provided by remix_tests.sol. I made a toy contract and a related test to show what the problem is: https://gist.github.com/...
3
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1answer
1k views

Convert address to string after solidity 0.5.x

After solidity 0.5.x release none of conversions from address to string appear to be working. I've tested all of them on remix and got errors like converting bytes to uint or something like this. ...
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1answer
70 views

Expected ')' but got identifier if(string name != users[name]){ ^--^

pragma solidity >=0.4.0 <0.7.0; contract NewHello{ mapping(address => string) public users; // contains a name for every address function updateUser(string memory name) public { ...