Program Structure
Every Expresiones program must begin with the program keyword followed by a block enclosed in curly braces:
program {
// Your code here
}
The program keyword is required and marks the entry point of your code.
Basic Program Example
Here’s a minimal valid Expresiones program:
program {
int x = 10;
int y = 5;
int resultado = x + y;
}
Statements
Expresiones supports three types of statements:
1. Variable Declarations
Declare variables with a type, identifier, and optional initialization:
int x; // Declaration without initialization
float pi = 3.14; // Declaration with initialization
bool activo = 1; // Boolean declaration
All declarations must end with a semicolon (;).
2. Assignments
Assign values to previously declared variables:
x = 20;
pi = 3.14159;
resultado = x + y * 2;
3. Control Flow Statements
Conditional statements allow branching logic:
if (x > 10) {
y = 100;
}
if (resultado > 15 && activo == 1) {
x = x + 100;
} else {
resultado = 999;
}
Code Blocks
Blocks are enclosed in curly braces {} and can contain zero or more statements:
{
int a = 5;
int b = 10;
int sum = a + b;
}
//:
// This is a comment
int x = 10; // Inline comment
// Multiple comment lines
// can be written like this
Multi-line comments (/* */) are not supported in Expresiones.
Identifiers
Identifiers (variable names) must follow these rules:
- Start with a letter (a-z or A-Z)
- Can contain letters, digits (0-9)
- Cannot start with a digit
- Case-sensitive
Valid identifiers:
x
valorUno
resultado
calculoFinal
activo
1variable // Cannot start with digit
x-value // Cannot contain hyphens
Complete Program Example
program {
// Variable declarations
int valorUno;
int valorDos;
int resultado;
int exito;
int error;
// Assignments
valorUno = 5;
valorDos = 10;
resultado = valorUno + valorDos;
// Control flow
if (resultado > 10) {
exito = 1;
} else {
error = 0;
}
}
Grammar Reference
The formal grammar structure:
root : PROGRAMA LLAVE_IZQ instrucciones+ LLAVE_DER EOF
instrucciones
: declaracion PUNTO_COMA
| asignacion PUNTO_COMA
| SI PAR_IZQ condicion PAR_DER bloque (SINO bloque)?
bloque : LLAVE_IZQ instrucciones* LLAVE_DER
declaracion : TIPO ID (ASIGNACION expr)?
asignacion : ID ASIGNACION expr