C++自学之路：3.1-简单变量。
#include
#include
int main(int argc, const char * argv[]) { using namespace std; int n_int = INT_MAX; short n_short = SHRT_MAX; long n_long = LONG_MAX; long long n_llong = LLONG_MAX; cout << "int is " << sizeof(n_int) << " bytes." << endl; cout << "short is " << sizeof(n_short) << " btyes." << endl; cout << "long is " << sizeof(n_long) << " bytes." << endl; cout << "long long " << sizeof(n_llong) << " bytes." << endl; cout << endl; cout << "Maxium values:" << endl; cout << "int:" << n_int << endl; cout << "short:" << n_short << endl; cout << "long:" << n_long << endl; cout << "long long:" << n_llong << endl; cout << "Minium int values:" << endl; cout << "Bits per byte = " << CHAR_BIT << endl; return 0; }
sizeof 指出，在使用8位字节的
系统中，int长度为4个字节，可以对类名或者变量名使用sizeof运算符，类名需要放在括号中，变量名括号可选。
cout << "short is " << sizeof(int) << " btyes." << endl;
cout << "short is " << sizeof n_short << " btyes." << endl;
#include
#define ZERO 0;
#include
int main(int argc, const char * argv[]) { using namespace std; short sam = SHRT_MAX; unsigned short sue = sam; cout << "Sam has " << sam << " dollars and Sue has " << sue; cout << " dollars deposited." << endl << "Add $1 to each accout." << endl << "Now "; sam = sam + 1; sue = sue + 1; cout << "Sam has " << sam << " dollars and Sue has " << sue; cout << " dollars deposited.\nPoor Sam!" << endl; sam = ZERO; sue = ZERO; cout << "Sam has " << sam << " dollars and Sue has " << sue; cout << " dollars deposited." << endl; cout << "Take $1 from each accout." << endl << "Now "; sam = sam - 1; sue = sue - 1; cout << "Sam has " << sam << " dollars and Sue has " << sue; cout << " dollars deposited." << endl << "Lucky Sue!" << endl; return 0; }
运行结果：
Sam has 32767 dollars and Sue has 32767 dollars deposited.
Add $1 to each accout.
Now Sam has -32768 dollars and Sue has 32768 dollars deposited.
Poor Sam!
Sam has 0 dollars and Sue has 0 dollars deposited.
Take $1 from each accout.
Now Sam has -1 dollars and Sue has 65535 dollars deposited.
Lucky Sue!
short 变量sam 和 unsigned short 变量 sue，分别设置最大值和最小值。short变量从最大值加1，取值从32768变成—32769。unsigned short变量从最大值加1并没有什么问题。short变量从最大值减1，没什么问题。unsigned short变量从最大值加1，从0变为65535。
如果超越了范围，其值将从范围另一端取值。
无符号类型：
unsigned short change;
unsigned int rovert;
unsigned quarterback;//unsigned 本身是 unsigned int 缩写。
unsigned long gone;
unsigned long long lang_lang;
//无符号类型的正值更大。
选择整型类型：
1.int 被设置为对目标计算机而言最为自然的长度。
2.如果变量表示的值不可能为负，如文档中的字数，则可以使用无符号类型，这样可以表示更大的值。
#include
using namespace std;
int main(int argc, const char * arvg[]) {
using namespace std;
in