int k; (circled) bool IsEven(int n); (circled) k-; <-- incorrect. Closest match is k--; (decrements k by one) if (k==1) { (circled) k += 1; (circled) }
b) State two advantages of using functions in program design.
Functions allow one to decompose a complex program into smaller, more easily understandable pieces. Functions allow code reuse. A function is defined only once, but it can be called (used) multiple times in a program.
bool IsPrime(int n) // Returns true if n>1 and the only divisors of n are 1 and n // Returns false otherwise (function body not shown)fill in the main() function below so that it prints all prime numbers between 1 and 10,000 to the console output cout. A prime number is an integer p for which the function invocation IsPrime(n) returns true. Consecutive numbers should be separated by spaces in the output.
One possibility: (important point: there should *not* be any commas in 10000 below) int main() { for (int i=2; i<=10000; i++) { if (IsPrime(i)) cout << i << " "; } return 0; } Another possibility: int main() { int i=2; while (i<=10000) { if (IsPrime(i)) cout << i << " "; i++; } return 0; }
a) int i=12; cout << i%5; output: 2 b) int j=9; cout << ++j; output: 10 c) int k=1; while (k/4 < 2) k*=3; cout << k; output: 9 d) bool flag=false; for (int i=1; i<=1000; i++) if (i%3 == 0) flag = !flag; if (flag) cout << "true"; else if (!flag) cout << "false"; output: true e) int lambda = 32; while (lambda > 0) { int k=lambda; while (k > 0) { cout << "*"; k /= 2; } cout << endl; lambda /= 3; output: ****** } **** ** *
int main() { double x error: missing final semicolon x = 3; warning, but no error: conversion from int to double y = 4.5; error: object named y has not been declared cout << the value of x+y equals << x+y; error: missing quotation marks return 0.0; warning, but no error: conversion from double to int }
bool UFO(int n) { while (n%2 == 0) n/=2; return (n==1); } Answer: UFO(n) returns true if n is a power of 2, and returns false otherwise. For example, UFO(32) returns true because 32 equals 2 to the 5th power, while UFO(7) returns false. By the way, UFO stands for "Unidentified Function Object".