Solidity String Declaration – Inside Function Guidelines

soliditystring

I tried to declare string inside my function but it doesn't work.

How to declare string inside function?

Best Answer

I suspect it has to do with some already answered question like Why do Solidity examples use bytes32 type instead of string?

However, a code like the one below seems to work around without declaring a string.

contract A{
        function f() constant returns(string){
            var s="hello";
            return s;
        }

    }

Related Solutions

Solidity String Length – How to Check String Length in a Contract

Just check if bytes(str).length is too big.

Mind: This does not show the number of characters! See the answer below if you need to know an exact length of a utf-8 encoded string. This will cost significantly more gas, however. Note that the utf-8 length will be at most the byte length.

Solidity Strings – How to Put a Variable Inside a String in Solidity

This would work if you do string concatenation. You may refer this question for string concatenation in solidity. The code may look like follow for string concatenation.

url_1 = "json(https://opensky-network.org/api/states/all?icao24";
url_2 = id;
url_3 = ")states[0][0]"

bytes memory burl_1 = bytes(url_1);
bytes memory burl_2 = bytes(url_2);
bytes memory burl_3 = bytes(url_3);

string memory url = string(burl_1.length + burl_2.length + burl_3.length);
bytes memory burl = bytes(url);

uint k = 0;
for (uint i = 0; i < burl_1.length; i++) burl[k++] = burl_1[i];
for (i = 0; i < burl_2.length; i++) burl[k++] = burl_2[i];
for (i = 0; i < burl_3.length; i++) burl[k++] = burl_3[i];

url = string(burl);

Best Answer

Related Solutions

Solidity String Length – How to Check String Length in a Contract

Solidity Strings – How to Put a Variable Inside a String in Solidity

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