静态常量变量 static const 变量,允许在一个类体中定义一个常量值,也可以
创建静态对象数组,包括const数组与非const数组\
//: C10:StaticArray.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 2000
// Copyright notice in Copyright.txt
// Initializing static arrays in classes
class Values {
// static consts are initialized in-place:
static const int scSize = 100;
static const long scLong = 100;
// Automatic counting works with static arrays.
// Arrays, Non-integral and non-const statics
// must be initialized externally:
static const int scInts[];
static const long scLongs[];
static const float scTable[];
static const char scLetters[];
static int size;
static const float scFloat;
static float table[];
static char letters[];
};
int Values::size = 100;
const float Values::scFloat = 1.1;
const int Values::scInts[] = {
99, 47, 33, 11, 7
};
const long Values::scLongs[] = {
99, 47, 33, 11, 7
};
const float Values::scTable[] = {
1.1, 2.2, 3.3, 4.4
};
const char Values::scLetters[] = {
'a', 'b', 'c', 'd', 'e',
'f', 'g', 'h', 'i', 'j'
};
float Values::table[4] = {
1.1, 2.2, 3.3, 4.4
};
char Values::letters[10] = {
'a', 'b', 'c', 'd', 'e',
'f', 'g', 'h', 'i', 'j'
};
int main() { Values v; } ///:~
利用全部类型的静态常量,可以在类内提供这些定义,但是对于其他的对象,
包括全部类型的数组,甚至它们为静态常量,必须为这些成员提供专门的
外部定义
无输出
也可以创建类的静态常量对象和这样的对象的数组
不过,不能使用“内联语法”初始化它们,这种语法对全部内建类型的静态常量
有效
//: C10:StaticObjectArrays.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 2000
// Copyright notice in Copyright.txt
// Static arrays of class objects
class X {
int i;
public:
X(int ii) : i(ii) {}
};
class Stat {
// This doesn't work, although
// you might want it to:
//! static const X x(100);
// Both const and non-const static class
// objects must be initialized externally:
static X x2;
static X xTable2[];
static const X x3;
static const X xTable3[];
};
X Stat::x2(100);
X Stat::xTable2[] = {
X(1), X(2), X(3), X(4)
};
const X Stat::x3(100);
const X Stat::xTable3[] = {
X(1), X(2), X(3), X(4)
};
int main() { Stat v; } ///:~
类对象的常量和非常量静态数组的初始化必须以相同的方式执行,它们遵守
典型的静态定义语法
无输出