C Programming FAQs: Frequently Asked Questions

Why use arrays in the first place? Why not use containers, particularly from the standard library? If arrays are a must, and if the elements require specific initializers, the answer is the {...} initializer syntax.

#include <iostream> using namespace std; class Stack { public: Stack(int maxLen=5) throw(); Stack(const Stack& s) throw(); // ... }; Stack::Stack(int maxLen) throw() { cout << "Stack: maxLen=" << maxLen << '\n'; } Stack::Stack(const Stack& s) throw() { cout << "Stack: copy ctor\n"; } int main() { // 'a' will be constructed with maxLen=7: Stack a(7); // All 4 stacks in 'b' will be constructed with maxLen=5 Stack b[4]; // c[0] will copy from a, c[1] maxLen=8, c[2] maxLen=7, // c[3] will be constructed without arguments (maxLen=5): Stack c[4] = { a, Stack(8), 7 }; }

The (annotated) output of this program follows.

Stack: maxLen=7 <-- 1 Stack: maxLen=5 <-- 2 Stack: maxLen=5 <-- 3 Stack: maxLen=5 <-- 4 Stack: maxLen=5 <-- 5 Stack: copy ctor <-- 6 Stack: maxLen=8 <-- 7 Stack: maxLen=7 <-- 8 Stack: maxLen=5 <-- 9

(1) This is a

(2) This is b[0]

(3) This is b[1]

(4) This is b[2]

(5) This is b[3]

(6) This is c[0]

(7) This is c[1]

(8) This is c[2]

(9) This is c[3]