solidity

Author: Mostafa Kamal

javascript-developer/solidity/contract.md

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+# contract
+
+as like other oop language solidity has contract that is similar to class.
+
+```sol
+contract Code4mk {
+    // code will be here
+}
+```
+
+## visibility
+
+Solidity has 4 types visibility.
+
+1. external
+2. internal
+3. public
+4. private
+
+### external
+
+`external` function can accessable from own contract and other contract too.
+
+```sol
+function test() pure external returns(string memory){
+    return('external function');
+}
+```
+
+* access by `this.f()`
+
+### public
+
+`public`  access from any where as like other oop language.
+
+### internal
+
+`internal` only accessable from internally.
+
+
+
+
+
+# source
+
+* [official contract](https://solidity.readthedocs.io/en/latest/contracts.html)

javascript-developer/solidity/index.md

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+
+
+# define solidity version
+
+on the top of code you need to assign solidity version with pragma
+
+```sol
+pragma solidity "0.5.1";
+```
+
+* string must be double quote.
+
+
+## constructor
+
+solidity constructor simillar other oop langauge.
+
+```sol
+contract Code4mk {
+    string name;
+    constructor(string memory _name) public {
+        name = _name;
+    }
+}

javascript-developer/solidity/modifier.md

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+# modifier
+
+* modifier change the function behaviour. it woeks as like middleware also.
+
+```sol
+modifier onlyOwner {
+        require(
+            msg.sender == owner,
+            "Only owner can call this function."
+        );
+        _;
+    }
+// use modifier
+function human() view public onlyOwner {
+    //
+}
+```
+
+* [video coursestro](https://coursetro.com/posts/code/101/Solidity-Modifier-Tutorial---Control-Functions-with-Modifiers)
+
+* [modifier official](https://solidity.readthedocs.io/en/latest/contracts.html#function-modifiers)
+* [video](https://youtu.be/qkBAwyJWjLA?list=PLL5pYVd8AWtQJ3Ne1nkBbrQpD7L8C36SF&t=397)

javascript-developer/solidity/struct-mapping.md

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+
+
+
+* https://medium.com/upstate-interactive/mappings-arrays-87afc697e64f
+* [video courestro](https://coursetro.com/posts/code/102/Solidity-Mappings-&-Structs-Tutorial)