Solidity! Invalid implicit conversion from string memory to bytes memory requested












3















pragma solidity ^0.5

contract ProofOfExistence {

// ... some code here

function proofFor(string memory document) public view returns(bytes32) {
return sha256(document);
}

// ... some more code here
}


Gives following error :




TypeError: Invalid type for argument in function call. Invalid
implicit conversion from string memory to bytes memory requested.




I am unable to understand why this error is coming.



UPDATE :



pragma solidity ^0.5;
// Proof of Existence contract, version 3
contract ProofOfExistence3 {
mapping (bytes32 => bool) private proofs;
// store a proof of existence in the contract state
function storeProof(bytes32 proof) public{
proofs[proof] = true;
}
// calculate and store the proof for a document
function notarize(string memory document) public {
**bytes32 proof = proofFor(document);**
storeProof(proof);
}
// helper function to get a document's sha256
function proofFor(bytes memory document) public pure returns (bytes32) {
return sha256(document);
}
// check if a document has been notarized
function checkDocument(string memory document) view public returns (bool) {
**bytes32 proof = proofFor(document);**
return hasProof(proof);
}
// returns true if proof is stored
function hasProof(bytes32 proof) view public returns(bool) {
return proofs[proof];


UPDATE ERROR After the update as suggested I am getting the same error but on the lines having ** ...** this time. Why is it coming now?
Thanks










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  • 2





    It's better if you can copy-paste your code, rather than attaching a screenshot

    – Achala Dissanayake
    1 hour ago
















3















pragma solidity ^0.5

contract ProofOfExistence {

// ... some code here

function proofFor(string memory document) public view returns(bytes32) {
return sha256(document);
}

// ... some more code here
}


Gives following error :




TypeError: Invalid type for argument in function call. Invalid
implicit conversion from string memory to bytes memory requested.




I am unable to understand why this error is coming.



UPDATE :



pragma solidity ^0.5;
// Proof of Existence contract, version 3
contract ProofOfExistence3 {
mapping (bytes32 => bool) private proofs;
// store a proof of existence in the contract state
function storeProof(bytes32 proof) public{
proofs[proof] = true;
}
// calculate and store the proof for a document
function notarize(string memory document) public {
**bytes32 proof = proofFor(document);**
storeProof(proof);
}
// helper function to get a document's sha256
function proofFor(bytes memory document) public pure returns (bytes32) {
return sha256(document);
}
// check if a document has been notarized
function checkDocument(string memory document) view public returns (bool) {
**bytes32 proof = proofFor(document);**
return hasProof(proof);
}
// returns true if proof is stored
function hasProof(bytes32 proof) view public returns(bool) {
return proofs[proof];


UPDATE ERROR After the update as suggested I am getting the same error but on the lines having ** ...** this time. Why is it coming now?
Thanks










share|improve this question









New contributor




Khalid168 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
















  • 2





    It's better if you can copy-paste your code, rather than attaching a screenshot

    – Achala Dissanayake
    1 hour ago














3












3








3








pragma solidity ^0.5

contract ProofOfExistence {

// ... some code here

function proofFor(string memory document) public view returns(bytes32) {
return sha256(document);
}

// ... some more code here
}


Gives following error :




TypeError: Invalid type for argument in function call. Invalid
implicit conversion from string memory to bytes memory requested.




I am unable to understand why this error is coming.



UPDATE :



pragma solidity ^0.5;
// Proof of Existence contract, version 3
contract ProofOfExistence3 {
mapping (bytes32 => bool) private proofs;
// store a proof of existence in the contract state
function storeProof(bytes32 proof) public{
proofs[proof] = true;
}
// calculate and store the proof for a document
function notarize(string memory document) public {
**bytes32 proof = proofFor(document);**
storeProof(proof);
}
// helper function to get a document's sha256
function proofFor(bytes memory document) public pure returns (bytes32) {
return sha256(document);
}
// check if a document has been notarized
function checkDocument(string memory document) view public returns (bool) {
**bytes32 proof = proofFor(document);**
return hasProof(proof);
}
// returns true if proof is stored
function hasProof(bytes32 proof) view public returns(bool) {
return proofs[proof];


UPDATE ERROR After the update as suggested I am getting the same error but on the lines having ** ...** this time. Why is it coming now?
Thanks










share|improve this question









New contributor




Khalid168 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












pragma solidity ^0.5

contract ProofOfExistence {

// ... some code here

function proofFor(string memory document) public view returns(bytes32) {
return sha256(document);
}

// ... some more code here
}


Gives following error :




TypeError: Invalid type for argument in function call. Invalid
implicit conversion from string memory to bytes memory requested.




I am unable to understand why this error is coming.



UPDATE :



pragma solidity ^0.5;
// Proof of Existence contract, version 3
contract ProofOfExistence3 {
mapping (bytes32 => bool) private proofs;
// store a proof of existence in the contract state
function storeProof(bytes32 proof) public{
proofs[proof] = true;
}
// calculate and store the proof for a document
function notarize(string memory document) public {
**bytes32 proof = proofFor(document);**
storeProof(proof);
}
// helper function to get a document's sha256
function proofFor(bytes memory document) public pure returns (bytes32) {
return sha256(document);
}
// check if a document has been notarized
function checkDocument(string memory document) view public returns (bool) {
**bytes32 proof = proofFor(document);**
return hasProof(proof);
}
// returns true if proof is stored
function hasProof(bytes32 proof) view public returns(bool) {
return proofs[proof];


UPDATE ERROR After the update as suggested I am getting the same error but on the lines having ** ...** this time. Why is it coming now?
Thanks







solidity error string bytes data-types






share|improve this question









New contributor




Khalid168 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




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Check out our Code of Conduct.









share|improve this question




share|improve this question








edited 47 mins ago







Khalid168













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asked 2 hours ago









Khalid168Khalid168

185




185




New contributor




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New contributor





Khalid168 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Khalid168 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.








  • 2





    It's better if you can copy-paste your code, rather than attaching a screenshot

    – Achala Dissanayake
    1 hour ago














  • 2





    It's better if you can copy-paste your code, rather than attaching a screenshot

    – Achala Dissanayake
    1 hour ago








2




2





It's better if you can copy-paste your code, rather than attaching a screenshot

– Achala Dissanayake
1 hour ago





It's better if you can copy-paste your code, rather than attaching a screenshot

– Achala Dissanayake
1 hour ago










2 Answers
2






active

oldest

votes


















1














Argument to sha256 should be in bytes. But you're passing document which is a string. Following would work.



function proofFor(bytes memory document) public pure returns(bytes32) {
return sha256(document);
}


And a side note - your function doesn't need to be view type since it is not viewing any storage items. This can be made a pure function which has neither side effects nor storage viewing. More details can be found here.



UPDATE :



If changing string to bytes gives errors at other function calls you can either convert them to bytes as well or else you can cast string to bytes as @Mikhail suggested. Then that would be;



function proofFor(string memory document) public pure returns(bytes32) {
return sha256(bytes (document));
}





share|improve this answer


























  • Thanks for the quick response! after changing the code as u suggested I am getting errors in the other part.

    – Khalid168
    1 hour ago











  • pragma solidity ^0.5; // Proof of Existence contract, version 3 contract ProofOfExistence3 { mapping (bytes32 => bool) private proofs; // store a proof of existence in the contract state function storeProof(bytes32 proof) public{ proofs[proof] = true; } // calculate and store the proof for a document function notarize(string memory document) public { bytes32 proof = proofFor(document); storeProof(proof); }

    – Khalid168
    1 hour ago











  • I have added the code but seems quite ugly here!

    – Khalid168
    59 mins ago






  • 1





    Thanks a lot for the guidance...Now the problem is solved!

    – Khalid168
    43 mins ago






  • 1





    Yeah done now !

    – Khalid168
    38 mins ago



















1














Should probably be



return sha256(bytes (document));





share|improve this answer
























  • Thanks a lot for help ! It's solved like this

    – Khalid168
    42 mins ago












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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes









1














Argument to sha256 should be in bytes. But you're passing document which is a string. Following would work.



function proofFor(bytes memory document) public pure returns(bytes32) {
return sha256(document);
}


And a side note - your function doesn't need to be view type since it is not viewing any storage items. This can be made a pure function which has neither side effects nor storage viewing. More details can be found here.



UPDATE :



If changing string to bytes gives errors at other function calls you can either convert them to bytes as well or else you can cast string to bytes as @Mikhail suggested. Then that would be;



function proofFor(string memory document) public pure returns(bytes32) {
return sha256(bytes (document));
}





share|improve this answer


























  • Thanks for the quick response! after changing the code as u suggested I am getting errors in the other part.

    – Khalid168
    1 hour ago











  • pragma solidity ^0.5; // Proof of Existence contract, version 3 contract ProofOfExistence3 { mapping (bytes32 => bool) private proofs; // store a proof of existence in the contract state function storeProof(bytes32 proof) public{ proofs[proof] = true; } // calculate and store the proof for a document function notarize(string memory document) public { bytes32 proof = proofFor(document); storeProof(proof); }

    – Khalid168
    1 hour ago











  • I have added the code but seems quite ugly here!

    – Khalid168
    59 mins ago






  • 1





    Thanks a lot for the guidance...Now the problem is solved!

    – Khalid168
    43 mins ago






  • 1





    Yeah done now !

    – Khalid168
    38 mins ago
















1














Argument to sha256 should be in bytes. But you're passing document which is a string. Following would work.



function proofFor(bytes memory document) public pure returns(bytes32) {
return sha256(document);
}


And a side note - your function doesn't need to be view type since it is not viewing any storage items. This can be made a pure function which has neither side effects nor storage viewing. More details can be found here.



UPDATE :



If changing string to bytes gives errors at other function calls you can either convert them to bytes as well or else you can cast string to bytes as @Mikhail suggested. Then that would be;



function proofFor(string memory document) public pure returns(bytes32) {
return sha256(bytes (document));
}





share|improve this answer


























  • Thanks for the quick response! after changing the code as u suggested I am getting errors in the other part.

    – Khalid168
    1 hour ago











  • pragma solidity ^0.5; // Proof of Existence contract, version 3 contract ProofOfExistence3 { mapping (bytes32 => bool) private proofs; // store a proof of existence in the contract state function storeProof(bytes32 proof) public{ proofs[proof] = true; } // calculate and store the proof for a document function notarize(string memory document) public { bytes32 proof = proofFor(document); storeProof(proof); }

    – Khalid168
    1 hour ago











  • I have added the code but seems quite ugly here!

    – Khalid168
    59 mins ago






  • 1





    Thanks a lot for the guidance...Now the problem is solved!

    – Khalid168
    43 mins ago






  • 1





    Yeah done now !

    – Khalid168
    38 mins ago














1












1








1







Argument to sha256 should be in bytes. But you're passing document which is a string. Following would work.



function proofFor(bytes memory document) public pure returns(bytes32) {
return sha256(document);
}


And a side note - your function doesn't need to be view type since it is not viewing any storage items. This can be made a pure function which has neither side effects nor storage viewing. More details can be found here.



UPDATE :



If changing string to bytes gives errors at other function calls you can either convert them to bytes as well or else you can cast string to bytes as @Mikhail suggested. Then that would be;



function proofFor(string memory document) public pure returns(bytes32) {
return sha256(bytes (document));
}





share|improve this answer















Argument to sha256 should be in bytes. But you're passing document which is a string. Following would work.



function proofFor(bytes memory document) public pure returns(bytes32) {
return sha256(document);
}


And a side note - your function doesn't need to be view type since it is not viewing any storage items. This can be made a pure function which has neither side effects nor storage viewing. More details can be found here.



UPDATE :



If changing string to bytes gives errors at other function calls you can either convert them to bytes as well or else you can cast string to bytes as @Mikhail suggested. Then that would be;



function proofFor(string memory document) public pure returns(bytes32) {
return sha256(bytes (document));
}






share|improve this answer














share|improve this answer



share|improve this answer








edited 40 mins ago

























answered 1 hour ago









Achala DissanayakeAchala Dissanayake

3,78781629




3,78781629













  • Thanks for the quick response! after changing the code as u suggested I am getting errors in the other part.

    – Khalid168
    1 hour ago











  • pragma solidity ^0.5; // Proof of Existence contract, version 3 contract ProofOfExistence3 { mapping (bytes32 => bool) private proofs; // store a proof of existence in the contract state function storeProof(bytes32 proof) public{ proofs[proof] = true; } // calculate and store the proof for a document function notarize(string memory document) public { bytes32 proof = proofFor(document); storeProof(proof); }

    – Khalid168
    1 hour ago











  • I have added the code but seems quite ugly here!

    – Khalid168
    59 mins ago






  • 1





    Thanks a lot for the guidance...Now the problem is solved!

    – Khalid168
    43 mins ago






  • 1





    Yeah done now !

    – Khalid168
    38 mins ago



















  • Thanks for the quick response! after changing the code as u suggested I am getting errors in the other part.

    – Khalid168
    1 hour ago











  • pragma solidity ^0.5; // Proof of Existence contract, version 3 contract ProofOfExistence3 { mapping (bytes32 => bool) private proofs; // store a proof of existence in the contract state function storeProof(bytes32 proof) public{ proofs[proof] = true; } // calculate and store the proof for a document function notarize(string memory document) public { bytes32 proof = proofFor(document); storeProof(proof); }

    – Khalid168
    1 hour ago











  • I have added the code but seems quite ugly here!

    – Khalid168
    59 mins ago






  • 1





    Thanks a lot for the guidance...Now the problem is solved!

    – Khalid168
    43 mins ago






  • 1





    Yeah done now !

    – Khalid168
    38 mins ago

















Thanks for the quick response! after changing the code as u suggested I am getting errors in the other part.

– Khalid168
1 hour ago





Thanks for the quick response! after changing the code as u suggested I am getting errors in the other part.

– Khalid168
1 hour ago













pragma solidity ^0.5; // Proof of Existence contract, version 3 contract ProofOfExistence3 { mapping (bytes32 => bool) private proofs; // store a proof of existence in the contract state function storeProof(bytes32 proof) public{ proofs[proof] = true; } // calculate and store the proof for a document function notarize(string memory document) public { bytes32 proof = proofFor(document); storeProof(proof); }

– Khalid168
1 hour ago





pragma solidity ^0.5; // Proof of Existence contract, version 3 contract ProofOfExistence3 { mapping (bytes32 => bool) private proofs; // store a proof of existence in the contract state function storeProof(bytes32 proof) public{ proofs[proof] = true; } // calculate and store the proof for a document function notarize(string memory document) public { bytes32 proof = proofFor(document); storeProof(proof); }

– Khalid168
1 hour ago













I have added the code but seems quite ugly here!

– Khalid168
59 mins ago





I have added the code but seems quite ugly here!

– Khalid168
59 mins ago




1




1





Thanks a lot for the guidance...Now the problem is solved!

– Khalid168
43 mins ago





Thanks a lot for the guidance...Now the problem is solved!

– Khalid168
43 mins ago




1




1





Yeah done now !

– Khalid168
38 mins ago





Yeah done now !

– Khalid168
38 mins ago











1














Should probably be



return sha256(bytes (document));





share|improve this answer
























  • Thanks a lot for help ! It's solved like this

    – Khalid168
    42 mins ago
















1














Should probably be



return sha256(bytes (document));





share|improve this answer
























  • Thanks a lot for help ! It's solved like this

    – Khalid168
    42 mins ago














1












1








1







Should probably be



return sha256(bytes (document));





share|improve this answer













Should probably be



return sha256(bytes (document));






share|improve this answer












share|improve this answer



share|improve this answer










answered 54 mins ago









Mikhail VladimirovMikhail Vladimirov

1,003314




1,003314













  • Thanks a lot for help ! It's solved like this

    – Khalid168
    42 mins ago



















  • Thanks a lot for help ! It's solved like this

    – Khalid168
    42 mins ago

















Thanks a lot for help ! It's solved like this

– Khalid168
42 mins ago





Thanks a lot for help ! It's solved like this

– Khalid168
42 mins ago










Khalid168 is a new contributor. Be nice, and check out our Code of Conduct.










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Khalid168 is a new contributor. Be nice, and check out our Code of Conduct.












Khalid168 is a new contributor. Be nice, and check out our Code of Conduct.
















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