CSC 212 Chapter 3, Fall 2013

 2003 Prentice Hall, Inc. All rights reserved. 1 Introduction • Use Functions when – Programs are long and complex – Performing the same statements frequently – Sharing a project • A function is a group of statements that are defined separately and referenced when needed Chapter 3 - Functions  2003 Prentice Hall, Inc. All rights reserved. 2 Introduction • A function is also called a module and dividing a program into subprograms is called Modular Programming (divide and conquer) • C++ Programs use new and “prepackaged” modules • Modular Programming has many advantages (easier testing, easier debugging, code reuse, readability, project sharing, simple programs)  2003 Prentice Hall, Inc. All rights reserved. 3 Math Library Functions • They perform common mathematical calculations – Include the header file <math.h> or <cmath> for the new C++ standard library • Functions are called by writing – functionName (argument); or – functionName(argument1, argument2, …); • Example cout << sqrt( 900.0 ); – The preceding statement would print 30 – All functions in math library return a double  2003 Prentice Hall, Inc. All rights reserved. 4 Math Library Functions • Function arguments can be – Constants • sqrt( 4 ); – Variables • sqrt( x ); – Expressions • sqrt( sqrt( x ) ) ; • sqrt( 3 - 6x );  2003 Prentice Hall, Inc. All rights reserved. 5 Method Desc ription Example ceil( x ) rounds x to the smallest integer not less than x ceil( 9.2 ) is 10.0 ceil( -9.8 ) is -9.0 cos( x ) trigonometric cosine of x (x in radians) cos( 0.0 ) is 1.0 exp( x ) exponential function ex exp( 1.0 ) is 2.71828 exp( 2.0 ) is 7.38906 fabs( x ) absolute value of x fabs( 5.1 ) is 5.1 fabs( 0.0 ) is 0.0 fabs( -8.76 ) is 8.76 floor( x ) rounds x to the largest integer not greater than x floor( 9.2 ) is 9.0 floor( -9.8 ) is -10.0 fmod( x, y ) remainder of x/y as a floating- point number fmod( 13.657, 2.333 ) is 1.992 log( x ) natural logarithm of x (base e) log( 2.718282 ) is 1.0 log( 7.389056 ) is 2.0 log10( x ) logarithm of x (base 10) log10( 10.0 ) is 1.0 log10( 100.0 ) is 2.0 pow( x, y ) x raised to power y (xy) pow( 2, 7 ) is 128 pow( 9, .5 ) is 3 sin( x ) trigonometric sine of x (x in radians) sin( 0.0 ) is 0 sqrt( x ) square root of x sqrt( 900.0 ) is 30.0 sqrt( 9.0 ) is 3.0 tan( x ) trigonometric tangent of x (x in radians) tan( 0.0 ) is 0 C ommonly used Math library func tions.  2003 Prentice Hall, Inc. All rights reserved. 6 Functions • Functions – Modularize a program • Local variables – Known only in the function in which they are defined – All variables declared in function definitions are local variables • Parameters – Local variables passed to function when called – Provide outside information  2003 Prentice Hall, Inc. All rights reserved. 7 Functions • Function prototype – Tells the compiler about argument type, number and order and also about the return type of the function – int square( int ); • Function takes an int and returns an int • Calling/invoking a function – square(x); – Parentheses are used in a call to a function • Pass argument x • Function gets its own copy of arguments – After function is finished, it passes back result  2003 Prentice Hall, Inc. All rights reserved. 8 Function Definitions • Format for function definition return-value-type function-name( parameter-list ) { declarations and statements } – Parameter list • Comma separated list of arguments – Data type needed for each argument • If no arguments, use void or leave blank – Return-value-type • Data type of result returned (use void if nothing returned) – declarations and statements • Form the function body  2003 Prentice Hall, Inc. All rights reserved. 9 Function Definitions • Example function int square( int y ) { return y * y; } • return keyword – Returns data, and control goes to function’s caller • If no data to return, use return; – Function ends when reaches right brace • Control goes to caller • Functions cannot be defined inside other functions  2003 Prentice Hall, Inc. All rights reserved. Outline 10 // Calculate the square of the integer from 1 to 10 #include <iostream> using namespace std; int square( int ); // function prototype int main() { // loop 10 times and calculate and output // square of x each time for ( int x = 1; x <= 10; x++ ) cout << square( x ) << " "; // function call cout << endl; return 0; // indicates successful termination } // end main Parentheses () cause function to be called. When done, it returns the result. Function prototype: specifies data types of arguments and return values. square expects and int, and returns an int.  2003 Prentice Hall, Inc. All rights reserved. Outline 11 // square function definition returns square of an integer int square( int y ) // y is a copy of argument to function { return y * y; // returns square of y as an int } // end function square 1 4 9 16 25 36 49 64 81 100 Definition of square. y is a copy of the argument passed. Returns y * y, or y squared.  2003 Prentice Hall, Inc. All rights reserved. Outline 12 // Finding the maximum of three integer numbers. #include <iostream> using namespace std; int maximum( int, int, int ); // function prototype int main() { int number1; int number2; int number3; cout << "Enter three integers: "; cin >> number1 >> number2 >> number3; // number1, number2 and number3 are arguments to // the maximum function call cout << "Maximum is: " << maximum( number1, number2, number3 ) << endl; return 0; // indicates successful termination Function maximum takes 3 arguments (all integer) and returns an integer.  2003 Prentice Hall, Inc. All rights reserved. Outline 13 } // end main // function maximum definition; // x, y and z are parameters int maximum( int x, int y, int z ) { int max = x; // assume x is largest if ( y > max ) // if y is larger, max = y; // assign y to max if ( z > max ) // if z is larger, max = z; // assign z to max return max; // max is largest value } // end function maximum Comma separated list for multiple parameters.  2003 Prentice Hall, Inc. All rights reserved. 14 Function Prototypes • Function prototype contains – Function name – Parameters (number and data type) – Return type (void if returns nothing) – Only needed if function definition after function call • Prototype must match function definition – Function prototype double maximum( double, double, double ); – Definition double maximum( double x, double y, double z ) { … }  2003 Prentice Hall, Inc. All rights reserved. 15 Function Prototypes • Function signature – Part of prototype with name and parameters • double maximum( double, double, double ); • Argument Coercion – Force arguments to be of proper type • Converting int (4) to double (4.0) cout << sqrt(4) – Conversion rules • Arguments usually converted automatically • Changing from double to int can truncate data – 3.4 to 3 – Mixed type goes to highest type (promotion) Function signature  2003 Prentice Hall, Inc. All rights reserved. 16 Function Prototypes Data types long double double float unsigned long int (synonymous with unsigned long) long int (synonymous with long) unsigned int (synonymous with unsigned) int unsigned short int (synonymous with unsigned short) short int (synonymous with short) unsigned char char bool (false becomes 0, true becomes 1) Promotion hierarc hy for built-in data types from highest to lowest.  2003 Prentice Hall, Inc. All rights reserved. 17 Header Files • Header files contain – Function prototypes – Definitions of data types and constants • Header files ending with .h – Programmer-defined header files #include “myheader.h” • Library header files #include <cmath>  2003 Prentice Hall, Inc. All rights reserved. 18 Random Number Generation • rand function (<cstdlib> or <stdlib.h>) – i = rand(); – Generates unsigned integer between 0 and RAND_MAX (usually 32767) • Scaling and shifting – Modulus (remainder) operator: % • 10 % 3 is 1 • x % y is between 0 and y – 1 – Example i = rand() % 6 + 1; • “Rand() % 6” generates a number between 0 and 5 (scaling) • “+ 1” makes the range 1 to 6 (shift)  2003 Prentice Hall, Inc. All rights reserved. 19 Random Number Generation • Next – Program to show distribution of rand() – Simulate 6000 rolls of a die – Print number of 1’s, 2’s, 3’s, etc. rolled – Should be roughly 1000 of each  2003 Prentice Hall, Inc. All rights reserved. Outline 20 // Roll a six-sided die 6000 times. #include <iostream> #include <iomanip> #include <cstdlib> // contains function prototype for rand using namespace std; int main() { int frequency1 = 0; int frequency2 = 0; int frequency3 = 0; int frequency4 = 0; int frequency5 = 0; int frequency6 = 0; int face; // represents one roll of the die  2003 Prentice Hall, Inc. All rights reserved. Outline 21 // loop 6000 times and summarize results for ( int roll = 1; roll <= 6000; roll++ ) { face = 1 + rand() % 6; // random number from 1 to 6 // determine face value and increment appropriate counter switch ( face ) { case 1: // rolled 1 ++frequency1; break; case 2: // rolled 2 ++frequency2; break; case 3: // rolled 3 ++frequency3; break; case 4: // rolled 4 ++frequency4; break; case 5: // rolled 5 ++frequency5; break;  2003 Prentice Hall, Inc. All rights reserved. Outline 22 case 6: // rolled 6 ++frequency6; break; default: // invalid value cout << "Program should never get here!"; } // end switch } // end for // display results in tabular format cout << "Face" << setw( 13 ) << "Frequency" << "\n 1" << setw( 13 ) << frequency1 << "\n 2" << setw( 13 ) << frequency2 << "\n 3" << setw( 13 ) << frequency3 << "\n 4" << setw( 13 ) << frequency4 << "\n 5" << setw( 13 ) << frequency5 << "\n 6" << setw( 13 ) << frequency6 << endl; return 0; // indicates successful termination } // end main Default case included even though it should never be reached. This is a matter of good coding style  2003 Prentice Hall, Inc. All rights reserved. Outline 23 Face Frequency 1 1003 2 1017 3 983 4 994 5 1004 6 999  2003 Prentice Hall, Inc. All rights reserved. 24 Random Number Generation • Calling rand() repeatedly – Gives the same sequence of numbers • Pseudorandom numbers – Preset sequence of "random" numbers – Same sequence generated whenever program run • To get different random sequences – Provide a seed value • Like a random starting point in the sequence • The same seed will give the same sequence – srand(seed); • <cstdlib> or <stdlib.h> • Used before rand() to set the seed  2003 Prentice Hall, Inc. All rights reserved. Outline 25 // Shifted, scaled integers produced by 1 + rand() % 6. #include <iostream> #include <iomanip> #include <cstdlib> // contains function prototype for rand using namespace std; int main() { // loop 20 times for ( int counter = 1; counter <= 20; counter++ ) { // pick random number from 1 to 6 and output it cout << setw( 10 ) << ( 1 + rand() % 6 ); // if counter divisible by 5, begin new line of output if ( counter % 5 == 0 ) cout << endl; } // end for structure Output of rand() scaled and shifted to be a number between 1 and 6.  2003 Prentice Hall, Inc. All rights reserved. Outline 26 return 0; // indicates successful termination } // end main 6 6 5 5 6 5 1 1 5 3 6 6 2 4 2 6 2 3 4 1  2003 Prentice Hall, Inc. All rights reserved. Outline 27 // Randomizing die-rolling program. #include <iostream> #include <iomanip> // contains prototypes for functions srand and rand #include <cstdlib> using namespace std; // main function begins program execution int main() { unsigned seed; cout << "Enter seed: "; cin >> seed; srand( seed ); // seed random number generator Setting the seed with srand().  2003 Prentice Hall, Inc. All rights reserved. Outline 28 // loop 10 times for ( int counter = 1; counter <= 10; counter++ ) { // pick random number from 1 to 6 and output it cout << setw( 10 ) << ( 1 + rand() % 6 ); // if counter divisible by 5, begin new line of output if ( counter % 5 == 0 ) cout << endl; } // end for return 0; // indicates successful termination } // end main Enter seed: 67 6 1 4 6 2 1 6 1 6 4 Enter seed: 432 4 6 3 1 6 3 1 5 4 2 Enter seed: 67 6 1 4 6 2 1 6 1 6 4 rand() gives the same sequence if it has the same initial seed.  2003 Prentice Hall, Inc. All rights reserved. 29 Random Number Generation • Can use the current time to set the seed – No need to explicitly set seed every time – srand( time( 0 ) ); – time( 0 ); • <ctime> or <time.h> • Returns current time in seconds • General shifting and scaling – Number = shiftingValue + rand() % scalingFactor – shiftingValue = first number in desired range – scalingFactor = width of desired range  2003 Prentice Hall, Inc. All rights reserved. 30 Example: Game of Chance and Introducing enum • Enumeration – Set of integers with identifiers enum typeName {constant1, constant2…}; – Constants start at 0 (default), incremented by 1 – Constants need unique names – Cannot assign integer to enumeration variable • Must use a previously defined enumeration type • Example enum Status {CONTINUE, WON, LOST}; Status enumVar; enumVar = WON; // cannot do enumVar = 1  2003 Prentice Hall, Inc. All rights reserved. 31 Example: Game of Chance and Introducing enum • Enumeration constants can have preset values enum Months { JAN = 1, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC}; – Starts at 1, increments by 1 • Next: craps simulator – Roll two dice – 7 or 11 on first throw: player wins – 2, 3, or 12 on first throw: player loses – 4, 5, 6, 8, 9, 10 • Value becomes player's "point" • Player must roll his point before rolling 7 to win  2003 Prentice Hall, Inc. All rights reserved. Outline 32 // Craps. #include <iostream> #include <stdlib> #include <time> using namespace std; int rollDice( void ); // function prototype int main() { // enumeration constants represent game status enum Status { CONTINUE, WON, LOST }; int sum; int myPoint; Status gameStatus; // can contain CONTINUE, WON or LOST Function to roll 2 dice and return the result as an int. Enumeration to keep track of the current game.  2003 Prentice Hall, Inc. All rights reserved. Outline 33 // randomize random number generator using current time srand( time( 0 ) ); sum = rollDice(); // first roll of the dice // determine game status and point based on sum of dice switch ( sum ) { // win on first roll case 7: case 11: gameStatus = WON; break; // lose on first roll case 2: case 3: case 12: gameStatus = LOST; break; switch statement determines outcome based on die roll.  2003 Prentice Hall, Inc. All rights reserved. Outline 34 // remember point default: gameStatus = CONTINUE; myPoint = sum; cout << "Point is " << myPoint << endl; break; // optional } // end switch // while game not complete ... while ( gameStatus == CONTINUE ) { sum = rollDice(); // roll dice again // determine game status if ( sum == myPoint ) // win by making point gameStatus = WON; else if ( sum == 7 ) // lose by rolling 7 gameStatus = LOST; } // end while  2003 Prentice Hall, Inc. All rights reserved. Outline 35 // display won or lost message if ( gameStatus == WON ) cout << "Player wins" << endl; else cout << "Player loses" << endl; return 0; // indicates successful termination } // end main // roll dice, calculate sum and display results int rollDice( void ) { int die1; int die2; int workSum; die1 = 1 + rand() % 6; // pick random die1 value die2 = 1 + rand() % 6; // pick random die2 value workSum = die1 + die2; // sum die1 and die2 Function rollDice takes no arguments, so has void in the parameter list.  2003 Prentice Hall, Inc. All rights reserved. Outline 36 // display results of this roll cout << "Player rolled " << die1 << " + " << die2 << " = " << workSum << endl; return workSum; // return sum of dice } // end function rollDice Player rolled 2 + 5 = 7 Player wins Player rolled 6 + 6 = 12 Player loses Player rolled 3 + 3 = 6 Point is 6 Player rolled 5 + 3 = 8 Player rolled 4 + 5 = 9 Player rolled 2 + 1 = 3 Player rolled 1 + 5 = 6 Player wins  2003 Prentice Hall, Inc. All rights reserved. 37 More on Variables • Variables have attributes – Have seen name, type, size, value – They also have: • Storage class – How long variable exists in memory • Scope – Where variable can be referenced in program • Linkage – For multiple-file program, which files can use it  2003 Prentice Hall, Inc. All rights reserved. 38 Variables: Storage Classes • Automatic storage class – Variable created when program enters its block – Variable destroyed when program leaves block – Only local variables of functions can be automatic • Automatic by default • keyword auto explicitly declares automatic – register keyword • Hint to place variable in high-speed register • Good for often-used items (loop counters) – Specify either register or auto, not both • register int counter = 1;  2003 Prentice Hall, Inc. All rights reserved. 39 Variables: Storage Classes • Static storage class – Variables exist for entire program • For functions, name exists for entire program – May not be accessible, scope rules still apply (more later) • static keyword – Local variables in function – Keeps value between function calls – Only known in own function • extern keyword – Default for global variables/functions • Globals: defined outside of a function block – Known in any function that comes after it  2003 Prentice Hall, Inc. All rights reserved. 40 Variables: Scope Rules • Scope – Portion of program where identifier can be used • File scope – Defined outside a function, known in all functions – Global variables, function definitions and prototypes • Function scope – Can only be referenced inside defining function – Only labels, e.g., identifiers with a colon (case:)  2003 Prentice Hall, Inc. All rights reserved. 41 Variables: Scope Rules • Block scope – Begins at declaration, ends at right brace } • Can only be referenced in this range – Local variables, function parameters – static variables still have block scope • Storage class separate from scope • Function-prototype scope – Parameter list of prototype – Names in prototype optional • Compiler ignores – In a single prototype, name can be used once  2003 Prentice Hall, Inc. All rights reserved. Outline 42 // A scoping example. #include <iostream> using namespace std; void a( void ); // function prototype void b( void ); // function prototype void c( void ); // function prototype int x = 1; // global variable int main() { int x = 5; // local variable to main cout << "local x in main's outer scope is " << x << endl; { // start new scope int x = 7; cout << "local x in main's inner scope is " << x << endl; } // end new scope cout << "local x in main's outer scope is " << x << endl; a(); b(); c() ; a(); b(); c(); cout << "\nlocal x in main is " << x << endl; return 0; // indicates successful termination } // end main  2003 Prentice Hall, Inc. All rights reserved. Outline 43 void a( void ) { int x = 25; // initialized each time a is called cout << endl << "local x in a is " << x << " on entering a" << endl; ++x; cout << "local x in a is " << x << " on exiting a" << endl; } // end function void b( void ) { // initialized only first time b is called static int x = 50; cout << endl << "local static x is " << x << " on entering b" << endl; ++x; cout << "local static x is " << x << " on exiting b" << endl; } // end function void c( void ) { cout << endl << "global x is " << x << " on entering c" << endl; x *= 10; cout << "global x is " << x << " on exiting c" << endl; } // end function  2003 Prentice Hall, Inc. All rights reserved. 44 Recursion • Recursive functions – Functions that call themselves – Can only solve a base case • If not base case – Break problem into smaller problem(s) – Launch new copy of function to work on the smaller problem (recursive call/recursive step) • Slowly converges towards base case • Function makes call to itself inside the return statement – Eventually base case gets solved • Answer works way back up, solves entire problem  2003 Prentice Hall, Inc. All rights reserved. 45 Recursion • Example: factorial n! = n * ( n – 1 ) * ( n – 2 ) * … * 1 – Recursive relationship ( n! = n * ( n – 1 )! ) 5! = 5 * 4! 4! = 4 * 3!… – Base case (1! = 0! = 1)  2003 Prentice Hall, Inc. All rights reserved. Outline 46 // Recursive factorial function. #include <iostream> #include <iomanip> using namespace std; unsigned long factorial( unsigned long ); // function prototype int main() { // Loop 10 times. During each iteration, calculate // factorial( i ) and display result. for ( int i = 0; i <= 10; i++ ) cout << setw( 2 ) << i << "! = " << factorial( i ) << endl; return 0; // indicates successful termination } // end main Data type unsigned long can hold an integer from 0 to 4 billion.  2003 Prentice Hall, Inc. All rights reserved. Outline 47 // recursive definition of function factorial unsigned long factorial( unsigned long number ) { // base case if ( number <= 1 ) return 1; // recursive step else return number * factorial( number - 1 ); } // end function factorial 0! = 1 1! = 1 2! = 2 3! = 6 4! = 24 5! = 120 6! = 720 7! = 5040 8! = 40320 9! = 362880 10! = 3628800 The base case occurs when we have 0! or 1!. All other cases must be split up (recursive step).  2003 Prentice Hall, Inc. All rights reserved. 48 Example Using Recursion: Fibonacci Series • Fibonacci series: 0, 1, 1, 2, 3, 5, 8... – Each number sum of two previous ones – Example of a recursive formula: • fib(n) = fib(n-1) + fib(n-2) • C++ code for Fibonacci function long fibonacci( long n ) { if ( n == 0 || n == 1 ) // base case return n; else return fibonacci( n - 1 ) + fibonacci( n – 2 ); }  2003 Prentice Hall, Inc. All rights reserved. 49 Example Using Recursion: Fibonacci Series f( 3 ) f( 1 ) f( 2 ) f( 1 ) f( 0 ) return 1 return 1 return 0 return + + return  2003 Prentice Hall, Inc. All rights reserved. 50 Example Using Recursion: Fibonacci Series • Order of operations – return fibonacci( n - 1 ) + fibonacci( n - 2 ); • Do not know which one executed first – C++ does not specify – Only &&, || and ?: guaranteed left-to-right evaluation • Recursive function calls – Each level of recursion doubles the number of function calls • 30th number = 2^30 ~ 4 billion function calls – Exponential complexity  2003 Prentice Hall, Inc. All rights reserved. Outline 51 // Recursive fibonacci function. #include <iostream> using namespace std; unsigned long fibonacci( unsigned long ); // function prototype int main() { unsigned long result, number; // obtain integer from user cout << "Enter an integer: "; cin >> number; // calculate fibonacci value for number input by user result = fibonacci( number ); // display result cout << "Fibonacci(" << number << ") = " << result << endl; return 0; // indicates successful termination The Fibonacci numbers get large very quickly, and are all non-negative integers. Thus, we use the unsigned long data type.  2003 Prentice Hall, Inc. All rights reserved. Outline 52 } // end main // recursive definition of function fibonacci unsigned long fibonacci( unsigned long n ) { // base case if ( n == 0 || n == 1 ) return n; // recursive step else return fibonacci( n - 1 ) + fibonacci( n - 2 ); } // end function fibonacci Enter an integer: 0 Fibonacci(0) = 0 Enter an integer: 1 Fibonacci(1) = 1 Enter an integer: 2 Fibonacci(2) = 1 Enter an integer: 3 Fibonacci(3) = 2  2003 Prentice Hall, Inc. All rights reserved. Outline 53 Enter an integer: 4 Fibonacci(4) = 3 Enter an integer: 5 Fibonacci(5) = 5 Enter an integer: 6 Fibonacci(6) = 8 Enter an integer: 10 Fibonacci(10) = 55 Enter an integer: 20 Fibonacci(20) = 6765 Enter an integer: 30 Fibonacci(30) = 832040 Enter an integer: 35 Fibonacci(35) = 9227465  2003 Prentice Hall, Inc. All rights reserved. 54 Recursion vs. Iteration // recursive factorial function unsigned long factorial( unsigned long number ) { if ( number <= 1 ) return 1; else return number * factorial( number - 1 ); } // factorial function using iteration unsigned long factorial( unsigned long number ) { unsigned long fact=1, count; for (count = 1; count <= number; count++) fact = fact * count; return fact; }  2003 Prentice Hall, Inc. All rights reserved. 55 Recursion vs. Iteration • Repetition – Iteration: explicit loop – Recursion: repeated function calls • Termination – Iteration: loop condition fails – Recursion: base case recognized • Both can have infinite loops • Balance between performance (iteration) and good software engineering (recursion)  2003 Prentice Hall, Inc. All rights reserved. 56 Functions with Empty Parameter Lists • Empty parameter lists – void or leave parameter list empty – Indicates function takes no arguments – Function print takes no arguments and returns no value • void print(); • void print( void );  2003 Prentice Hall, Inc. All rights reserved. Outline 57 // Functions that take no arguments. #include <iostream> using namespace std; void function1(); // function prototype void function2( void ); // function prototype int main() { function1(); // call function1 with no arguments function2(); // call function2 with no arguments return 0; // indicates successful termination } // end main  2003 Prentice Hall, Inc. All rights reserved. Outline 58 // function1 uses an empty parameter list to specify that // the function receives no arguments void function1() { cout << "function1 takes no arguments" << endl; } // end function1 // function2 uses a void parameter list to specify that // the function receives no arguments void function2( void ) { cout << "function2 also takes no arguments" << endl; } // end function2 function1 takes no arguments function2 also takes no arguments  2003 Prentice Hall, Inc. All rights reserved. 59 Inline Functions • Inline functions – Keyword inline before function definition – Asks the compiler to copy code into program instead of making function call • Reduce function-call overhead • Compiler can ignore inline – Good for small, often-used functions • Example inline double cube( const double s ) { return s * s * s; } – const tells compiler that function does not modify s  2003 Prentice Hall, Inc. All rights reserved. Outline 60 #include <iostream> using namespace std; // Definition of inline function cube. Definition of function // appears before function is called, so a function prototype // is not required. First line of function definition acts as // the prototype. inline double cube( const double side ) { return side * side * side; // calculate cube } // end function cube int main() { double sideValue; cout << "Enter the side length of your cube: "; cin >> sideValue; // calculate cube of sideValue and display result cout << "Volume of cube with side " << sideValue << " is " << cube( sideValue ) << endl; return 0; // indicates successful termination } // end main