Single-Result Functions Section /25/11

Programming Assignment On website.

Reading For Today: Sec. 5.1, pp For Monday: Sec. 4.1 & 4.2, pp

Functions Have discussed math library functions Can create your own functions

Example ch5/circle.cpp – Has a function to find the area of a circle. prototype – declares return-type, name, and parameters function call – name and arguments definition – describes how function computes the value it returns

Single-Result Function Definition // Comment w/ purpose and preconditions resultType functionName( parameter list) // header { // function body Declarations of local variables Statements to find a result Return statement to send back result }

#include //maximum finds the maximum of //three integers, x, y, z //Pre: x, y, and z must be set int maximum(int x, int y, int z); //prototype w/ 3 parameters int main(){ int a,b,c; cout "; cin >> a >> b >> c; cout << "Max is " << maximum(a,b,c)//call with <<endl; //3 arguments return 0; }

//FUNCTION DEFINITION- follows main int maximum(int x, int y, int z)//HEADER { //BODY int max = x; if (y > max)‏ max = y; if (z > max)‏ max = z; return max; }

Arguments and Parameters Arguments are values sent to function Parameters (formal parameters) are dummy variables that receive the information

Arguments and Parameters Must match in type and number – a,b,c & x,y,z – three ints Paired in the order that they appear

Local variables double circleArea(double r) { double a; a = PI * pow(r,2.0); return a; } a is a local variable invisible to main program

return statement double circleArea(double r) { double a; a = PI * pow(r,2.0); return a; } return a Sends value back to call

Boolean Function Returns a bool Can be used in an if statement example – ch5/factor.cpp

Function Write a function that takes a date of birth (mo, da, yr) and today's date(mo, da, yr) and returns a person's age in years. Disregard extra months and days. birthday.cpp has program. We need to add the function.

Question Write an algorithm for a function that takes an exam score and returns a letter grade. Write the function definition Write a main program to test the function. – Called a driver