Overview Expressions in Expresiones are combinations of values, variables, operators, and parentheses that evaluate to a single value.
Expression Types Numeric Literals Direct numeric values:
10 // Integer literal 42 // Integer literal 3.14 // Float literal 0.5 // Float literal
Variable References Use variable names to reference their values:
int x = 10; int y = x; // y gets the value of x int z = x + y; // Use variables in expressions
Arithmetic Expressions Expresiones supports four basic arithmetic operations:
Addition (+) Adds two values
Subtraction (-) Subtracts the second value from the first
Multiplication (*) Multiplies two values
Division (/) Divides the first value by the second
Basic Arithmetic program { int x = 10; int y = 5; int suma = x + y; // 15 int resta = x - y; // 5 int producto = x * y; // 50 int division = x / y; // 2 }
Operator Precedence Expresiones follows standard mathematical operator precedence:
Parentheses
Expressions inside () are evaluated first
Multiplication and Division
* and / operators (left-to-right)
Addition and Subtraction
+ and - operators (left-to-right)
Precedence Examples program { int x = 10; int y = 5; // Multiplication before addition int resultado = x + y * 2; // 10 + (5 * 2) = 20 // Division before subtraction int calc = x - y / 5; // 10 - (5 / 5) = 9 // Multiple operations int complejo = x + y * 2 - 8; // 10 + (5 * 2) - 8 = 12 }
Without parentheses, multiplication and division are always performed before addition and subtraction.
Parentheses Use parentheses to override default precedence or improve clarity:
program { int x = 10; int y = 5; // Force addition first int resultado = (x + y) * 2; // (10 + 5) * 2 = 30 // Complex expression with parentheses int calculoFinal = (x - 90 + y) / 5; // (10 - 90 + 5) / 5 = -15 // Multiple nested parentheses int complejo = ((x + y) * 2) - 8; // ((10 + 5) * 2) - 8 = 22 }
Nested Parentheses program { int a = 5; int b = 3; int c = 2; // Innermost parentheses evaluated first int resultado = ((a + b) * c) + 1; // ((5 + 3) * 2) + 1 = 17 }
Expression Grammar The formal grammar for expressions:
expr: expr (MULT | DIV) expr // Multiplication/Division | expr (SUMA | RESTA) expr // Addition/Subtraction | NUMERO // Numeric literal | ID // Variable reference | PAR_IZQ expr PAR_DER // Parenthesized expression
The grammar defines precedence implicitly through rule ordering: multiplication/division before addition/subtraction.
Complete Examples Example 1: Basic Arithmetic program { int valorUno = 5; int valorDos = 10; int resultado = valorUno + valorDos; // 15 }
Example 2: Operator Precedence program { int x = 10; int y = 5; int resultado = 0; // Multiplication before addition // 10 + 5 * 2 = 20 resultado = x + y * 2; }
Example 3: Complex Expression program { int x = 10; int y = 5; // Nested operations with parentheses x = x + 100; // x = 110 y = y * y; // y = 25 // (110 - 90 + 25) / 5 = 45 / 5 = 9 int calculoFinal = (x - 90 + y) / 5; }
Example 4: Float Expressions program { float pi = 3.14; int radius = 10; // Mixed int and float arithmetic float area = pi * radius; // 31.4 }
Expression Evaluation Left-to-Right Evaluation Operators with the same precedence are evaluated left-to-right:
int x = 10 - 5 - 2; // (10 - 5) - 2 = 3 int y = 20 / 5 / 2; // (20 / 5) / 2 = 2 int z = 2 * 3 * 4; // (2 * 3) * 4 = 24
Mixed Precedence // Step-by-step evaluation: int resultado = 10 + 5 * 2 - 8 / 4; // Step 1: 5 * 2 = 10 // Step 2: 8 / 4 = 2 // Step 3: 10 + 10 = 20 // Step 4: 20 - 2 = 18 // resultado = 18
Best Practices
Use Parentheses for Clarity Even when not required, parentheses improve readability int x = (a + b) * c; // Clear intent
Break Complex Expressions Split complex calculations into multiple statements int temp = x + y; int resultado = temp * 2;
Mind the Precedence Remember: * and / before + and - int x = 10 + 5 * 2; // 20, not 30
Use Meaningful Names Choose variable names that describe the value int area = width * height;