int數與多枚舉值互轉

在C/C++在C/C++的開發中經常會遇到各種數據類型互轉的情況，正常的互轉有：單個枚舉轉int數，int數轉float數，float數轉double數等。但是我們有時也會遇到多個枚舉值與數字互轉的情形（例如多個算法類型枚舉開啟標志轉成數字，這個數字來表示多個標志位，按位來表示）。這樣一個數字就能表示很多個標志位了，針對內存較少的嵌入式設備，這么操作可以達到節約內存消耗，提高程序運行效率的目的。

Demo示例

demo核心知識點：通過位運算符（布爾位運算符："~"、"&"、"|"；移位運算符："<<"）實現int數與多枚舉值互轉。
Code:

#include <iostream>using namespace std;int nFlag = 0; //用移位表示各個枚舉的開關 typedef enum {TYPEA, //A開啟，則nflag為1=0x00000001TYPEB, //B開啟，則nflag為2=0x00000010TYPEC, //C開啟，則nflag為4=0x00000100TYPED, //D開啟，則nflag為8=0x00001000TYPENUM //枚舉最大值，計數用 }EMTypeNum;void int2enum (int n) {if(n&(0x01<<TYPEA)){//為真cout << "TYPEA is ON\n";}else{//為假cout << "TYPEA is OFF\n";}if(n&(0x01<<TYPEB)){//為真cout << "TYPEB is ON\n";}else{//為假cout << "TYPEB is OFF\n";}if(n&(0x01<<TYPEC)){//為真cout << "TYPEC is ON\n";}else{//為假cout << "TYPEC is OFF\n";}if(n&(0x01<<TYPED)){//為真cout << "TYPED is ON\n";}else{//為假cout << "TYPED is OFF\n";} } void enum2int(EMTypeNum eMType, bool bOn) {if(bOn){nFlag |= (0x01 << eMType);}else{nFlag &= ~(0x01 << eMType);}cout << "nFlag:" << nFlag << endl; }int main() {int i = 0;for(i = 0; i < TYPENUM;i++){enum2int((EMTypeNum)i, true);int2enum(nFlag);cout << endl;}for(i = 0; i < TYPENUM;i++){enum2int((EMTypeNum)i, false);int2enum(nFlag); cout << endl;}return 0; }

Result:

nFlag:1 TYPEA is ON TYPEB is OFF TYPEC is OFF TYPED is OFFnFlag:3 TYPEA is ON TYPEB is ON TYPEC is OFF TYPED is OFFnFlag:7 TYPEA is ON TYPEB is ON TYPEC is ON TYPED is OFFnFlag:15 TYPEA is ON TYPEB is ON TYPEC is ON TYPED is ONnFlag:14 TYPEA is OFF TYPEB is ON TYPEC is ON TYPED is ONnFlag:12 TYPEA is OFF TYPEB is OFF TYPEC is ON TYPED is ONnFlag:8 TYPEA is OFF TYPEB is OFF TYPEC is OFF TYPED is ONnFlag:0 TYPEA is OFF TYPEB is OFF TYPEC is OFF TYPED is OFF

結束寄語

有關int數與多枚舉值互轉的介紹就到此結束啦！下篇博文與各位再見面~

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