【C++】setw函数的用法和作用【原创技术】.doc

作用：setw(4)是定义字段长度的函数用法：/题目：结构体成员变量/作者：武叶/创作时间：2012年4月21日/使用语言：C+#includeiostream.h#includeiomanip.hstruct studentint num;char name20;char sex;int age;stu=97001,lin lin,F,19;void main()coutsetw(7)stu.numsetw(20)setw(3)stu.sexsetw(3) 1000#pragma once#endif#ifdef _cplusplus#ifndef _INC_IOMANIP#define _INC_IOMANIP#if !defined(_WIN32) & !defined(_MAC)#error ERROR: Only Mac or Win32 targets supported!#endif#ifdef _MSC_VER/ Currently, all MS C compilers for Win32 platforms default to 8 byte/ alignment.#pragma pack(push,8)#include #endif / _MSC_VER#include #ifdef _MSC_VER#pragma warning(disable:4514) / disable unwanted /W4 warning/ #pragma warning(default:4514) / use this to reenable, if necessary#endif / _MSC_VER/ #define _MKMANIP(X) #define X#(T) _#X#_ # T/ _MKMANIP(SMANIP);/ _MKMANIP(SAPP);/ _MKMANIP(IMANIP);/ _MKMANIP(IAPP);/ _MKMANIP(OMANIP);/ _MKMANIP(OAPP);/ _MKMANIP(IOMANIP);/ _MKMANIP(IOAPP);#define SMANIP(T) _SMANIP_#T#define SAPP(T) _SAPP_#T#define IMANIP(T) _IMANIP_#T#define IAPP(T) _IAPP_#T#define OMANIP(T) _OMANIP_#T#define OAPP(T) _OAPP_#T#define IOMANIP(T) _IOMANIP_#T#define IOAPP(T) _IOAPP_#T#define IOMANIPdeclare(T) class SMANIP(T) public: SMANIP(T)(ios& (*f)(ios&,T), T t) : _fp(f), _tp(t) friend istream& operator(istream& s, const SMANIP(T) & sm) (*(sm._fp)(s,sm._tp); return s; friend ostream& operator(istream& s, IMANIP(T) & sm) (*sm._fp)(s,sm._tp); return s; private: istream& (* _fp)(istream&,T); T _tp; ; class IAPP(T) public: IAPP(T)( istream& (*f)(istream&,T) : _fp(f) IMANIP(T) operator()(T t) return IMANIP(T)(_fp,t); private: istream& (* _fp)(istream&,T); ; class OMANIP(T) public: OMANIP(T)(ostream& (*f)(ostream&,T), T t) : _fp(f), _tp(t) friend ostream& operator(iostream& s, IOMANIP(T) & sm) (*sm._fp)(s,sm._tp); return s; friend ostream& operator(iostream& s, IOMANIP(T) & sm) (*sm._fp)(s,sm._tp); return s; private: iostream& (* _fp)(iostream&,T); T _tp; ; class IOAPP(T) public: IOAPP(T)( iostream& (*f)(iostream&,T) : _fp(f) IOMANIP(T) operator()(T t) return IOMANIP(T)(_fp,t); private: iostream& (* _fp)(iostream&,T); ; IOMANIPdeclare(int)IOMANIPdeclare(long)inline ios& _resetiosflags(ios& s, long _flg) s.setf(0,_flg); return s; inline ios& _setfill(ios& s, int _fc) s.fill(char)_fc); return s; inline ios& _setiosflags(ios& s, long _flg) s.setf(_flg); return s; inline ios& _setprecision(ios& s, int _pre) s.precision(_pre); return s; inline ios& _setw(ios& s, int _wid) s.width(_wid); return s; inline SMANIP(long) resetiosflags(long _l) return SMANIP(long)(_resetiosflags, _l); inline SMANIP(int) setfill(int _m) return SMANIP(int)(_setfill, _m); inline SMANIP(long) setiosflags(long _l) return SMANIP(long)(_setiosflags, _l); inline SMANIP(int) setprecision(int _p) return SMANIP(int)(_setprecision, _p); inline SMANIP(int) setw(int _w) return SMANIP(int)(_setw, _w); / Restore previous packing#ifdef _MSC