Introduction to the Solidity Programming Language/

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Strings

Strings

Learn about strings in Solidity.

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In Solidity, the string keyword is used to specify the string data type. It represents and stores sequences of characters. The syntax of Solidity is influenced by languages like Python, C++, and JavaScript, incorporating their linguistic constructs. Here’s an example of a string in Solidity:

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Solidity string example with zero-based indexing
Solidity string example with zero-based indexing

Note: String indexes start at 0, following the zero-based indexing convention commonly used in programming.

These strings are essentially dynamic arrays containing a mix of characters, which can range from alphabets and numbers to special symbols and spaces. Solidity stores data in strings using UTF-8 encoding. Both double quotes (" ") and single quotes (' ') can be used for string literals in Solidity, as follows:

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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;
contract HelloWorld {
    // The greet variable is of type string with double quotes ("")
    string public greet = "Hello World!";
    // The welcome variable is of type string with single quotes ('')
    string public welcome = 'Hello World!';
    string public word;
    // Using a function to set the string
    function setString() public {
        word = "hey";
    }
    // Using a function to update the string by taking a new string as a parameter
    function updateString(string memory _word) public {
        word = _word;
    }
}

  • Line 4: We declare a contract named HelloWorld.

  • Line 6: We introduce a public state variable named greet, categorized as the string type, and initialize it with the value Hello World! using double quotes ("").

  • Line 8: We declare another public state variable named welcome. It’s also of type string and is initialized with the value Hello World! using single quotes ('').

  • Line 10: We declare a public state variable named word, typed as string, without providing any initial value.

  • Lines 13–15: We define a function named setString() with the public visibility specifier. This function sets the value ...