Solidity Error – Fixing Expected Primary Expression Error in Solidity ^0.8.0

solidity

I am trying to use any of the uint to string function implementations from the below links.

How to convert uint to string in solidity?

How to convert string to int

Conversion of uint to string

However in pragma solidity ^0.8.0 the compiler show the following error:

ParserError: Expected primary expression.

Is there a workaround?

This implementation for example produces that error

function uintToString(uint v) public returns (string memory) {
    uint maxlength = 100;
    bytes memory reversed = new bytes(maxlength);
    uint i = 0;
    while (v != 0) {
        uint remainder = v % 10;
        v = v / 10;
        reversed[i++] = byte(48 + remainder);
    }
    bytes memory s = new bytes(i); // i + 1 is inefficient
    for (uint j = 0; j < i; j++) {
        s[j] = reversed[i - j - 1]; // to avoid the off-by-one error
    }
    string memory str = string(s);  // memory isn't implicitly convertible to storage
    return str;
}

Best Answer

You cannot convert a uint256 to bytes1 directly, but if you convert it to uint8 first it works:

reversed[i++] = bytes1(uint8(48 + remainder));

So the full code looks like this:

function uintToString(uint v) public pure returns (string memory) {
    uint maxlength = 100;
    bytes memory reversed = new bytes(maxlength);
    uint i = 0;
    while (v != 0) {
        uint remainder = v % 10;
        v = v / 10;
        reversed[i++] = bytes1(uint8(48 + remainder));
    }
    bytes memory s = new bytes(i); // i + 1 is inefficient
    for (uint j = 0; j < i; j++) {
        s[j] = reversed[i - j - 1]; // to avoid the off-by-one error
    }
    string memory str = string(s);  // memory isn't implicitly convertible to storage
    return str;
}

Related Solutions

Solidity – Compile Error: Expected Primary Expression

Here's your modified code:

pragma solidity ^0.4.0;

contract user {

    address public owner;

    function user() {
        owner = msg.sender;
    }

    function kill() {
        suicide(owner);
    }

    modifier onlyOwner {
        if (msg.sender != owner) {
            throw;
        } else {
            _;
        }
    }
}

The only problem with your code is that I had to replace your - with a _;. See Are underscores `_` in modifiers code or are they just meant to look cool? for more information on the _ modifiers.

Your modified code then compiles perfectly in the Solidity realtime compiler and runtime:

Solidity Conversion – Parse an Integer to a String in Solidity

try this code :

function bytes32ToString (bytes32 data) returns (string) {
    bytes memory bytesString = new bytes(32);
    for (uint j=0; j<32; j++) {
      byte char = byte(bytes32(uint(data) * 2 ** (8 * j)));
      if (char != 0) {
        bytesString[j] = char;
      }
    }

    return string(bytesString);
  }

   function My_integ(bytes32 myInteger) returns (string){

        string memory myString= bytes32ToString( myInteger );
return myString;
   }

Best Answer

Related Solutions

Solidity – Compile Error: Expected Primary Expression

Solidity Conversion – Parse an Integer to a String in Solidity

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