Tipos de valor
uint, address, bool y bytes
Tipos de valor es una lección gratuita de Web3 & DApp Development Fundamentals en CoddyKit. Esta es la lección 1 de 4. Puedes leer la lección completa abajo gratuitamente — luego la practicas en el navegador con un editor de código integrado y un tutor de IA 24/7. Forma parte de la ruta de aprendizaje de Web3 & DApp Development Fundamentals, y tu progreso se sincroniza en la web y la app de CoddyKit. El curso de Web3 & DApp Development Fundamentals incluye 4 lecciones en total.
Partes de esta lección aún no han sido traducidas y se muestran en inglés.
What Are Value Types?
Value types in Solidity hold their data directly and are copied whenever they are assigned to a variable or passed to a function.
This is different from reference types (arrays, structs, mappings) which point to a shared location. Value types include bool, integers, address, and fixed-size bytes.
- Always copied on assignment
- Stored compactly
- Predictable gas cost
Booleans
The bool type holds either true or false. It is the result of comparison and logical operators.
Solidity supports ! (not), && (and), || (or). Logical operators short-circuit, just like in most languages.
<code>bool isActive = true;
bool hasPaid = false;
bool ready = isActive && !hasPaid;</code>Unsigned Integers
uint stores non-negative whole numbers. uint is an alias for uint256.
You can choose smaller sizes in steps of 8 bits: uint8, uint16, ... up to uint256. Smaller types can save storage when packed together in a struct.
<code>uint256 balance = 1000;
uint8 smallCount = 255; // max value for uint8</code>Signed Integers
int stores values that can be negative or positive. int is an alias for int256.
An int8 ranges from -128 to 127. Use signed integers only when negatives are genuinely possible, since they are easy to misuse.
<code>int256 temperature = -15;
int8 delta = 100;</code>Overflow Protection
Since Solidity 0.8.0, arithmetic automatically reverts on overflow and underflow. You no longer need SafeMath for basic safety.
If you intentionally want wrapping behavior for gas savings, wrap the math in an unchecked block.
<code>uint8 x = 255;
// x + 1 would revert (overflow)
unchecked {
x = x + 1; // wraps to 0
}</code>The address Type
An address holds a 20-byte Ethereum account identifier. It can refer to a wallet (EOA) or a contract.
The address type exposes members like .balance (in wei) and methods such as .transfer() and .send().
<code>address owner = 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4;
uint256 bal = owner.balance;</code>address vs address payable
A plain address cannot receive Ether directly. To send funds you need address payable, which adds .transfer() and .send().
You convert between them explicitly with payable(addr).
<code>address recipient = msg.sender;
address payable wallet = payable(recipient);
wallet.transfer(1 ether);</code>Fixed-Size Bytes
Solidity offers fixed-size byte arrays from bytes1 to bytes32. These are value types and are cheaper than dynamic bytes when the length is known.
They are useful for hashes, identifiers, and short fixed data.
<code>bytes32 hash = keccak256(abi.encodePacked('hello'));
bytes1 firstByte = hash[0];</code>Enums
An enum defines a custom type with a fixed set of named constants. Internally each value is a small uint starting at 0.
Enums make state machines readable, such as the status of an order.
<code>enum Status { Pending, Shipped, Delivered }
Status public current = Status.Pending;
function ship() public {
current = Status.Shipped;
}</code>Literals and Units
Solidity provides handy unit suffixes. Ether units: wei, gwei, ether. Time units: seconds, minutes, hours, days, weeks.
1 ether equals 10**18 wei.
<code>uint256 fee = 1 ether; // 1000000000000000000 wei
uint256 timeout = 2 days; // 172800 seconds</code>Default Values
Solidity has no null. Every value type has a zero default: uint is 0, bool is false, address is the zero address 0x0...0.
Checking against the zero address is a common guard.
<code>address public admin; // defaults to address(0)
function setAdmin(address a) public {
require(a != address(0), 'zero address');
admin = a;
}</code>Quick Check
Test your understanding of Solidity value types.
Recap
You learned the core value types in Solidity:
boolfor true/false logicuint/intwith built-in overflow protection since 0.8.0addressandaddress payablefor accounts and transfers- Fixed
bytesN,enum, and unit literals like1 ether
Remember: value types are copied, and every type has a zero default value.
Preguntas frecuentes
¿La lección «Tipos de valor» es gratis?
Sí — el texto completo de «Tipos de valor» es gratis para leer aquí en la web. Para practicarla de forma interactiva (editor de código integrado y tutor de IA 24/7) y desbloquear el resto del curso de Web3 & DApp Development Fundamentals, actualiza a CoddyKit PRO. El curso de Web3 & DApp Development Fundamentals incluye 4 lecciones en total.
¿Qué aprenderé en «Tipos de valor»?
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