cs31 lecture 2

Mpg m g 2gasleft c g 3return gasleft mpg return 11 a

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Unformatted text preview: ed 1.mpg := m / g 2.gasLeft := c – g 3.return gasLeft * mpg return 11 A few observations x New variables can be introduced in the algorithm as New needed needed x You don’t need to use a variable with ‘return’, you can use You an expression an x Informal definition: Informal Variable: an identifier Expression: one of: • • • • variable variable ‘operator’ expression (where ‘operator’ is +, -, /, …) expression ‘operator’ variable number 12 Using an algorithm in another algorithm Algorithm ComputeMilesLeft2: IInput: nput: • m: number of miles since last refuel • g: number of gallons consumed since last refuel • c: the capacity of the gas tank (in gallons) Output: • milesToRefuel: the number of miles before refuel is needed 1.mpg := MPG(m,g) 2.gasLeft := c – g 3.return gasLeft * mpg return 13 Calling another algorithm x Convention: use the algorithm name, and pass all inputs Convention: as arguments in parenthesis as x For the arguments, it can be a variable (its value is being For passed), or directly a numerical value passed), Examples: Examples: • • • foo(12) MilesToRefuel(x, y, z) MilesToRefuel(100, x, 15) x The names of the variables are the names from the caller x The algorithm returns some value: its output 14 Comments on (informal)...
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