在C/C++在C/C++的开发中经常会遇到各种数据类型互转的情况，正常的互转有：单个枚举转int数，int数转float数，float数转double数等。但是我们有时也会遇到多个枚举值与数字互转的情形（例如多个算法类型枚举开启标志转成数字，这个数字来表示多个标志位，按位来表示）。这样一个数字就能表示很多个标志位了，针对内存较少的嵌入式设备，这么操作可以达到节约内存消耗，提高程序运行效率的目的。
Demo示例
demo核心知识点：通过位运算符（布尔位运算符："~"、"&"、"|"；移位运算符："<<"）实现int数与多枚举值互转。
Code:
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#include <iostream>using namespace std;int nFlag = 0; //用移位表示各个枚举的开关typedef enum{ TYPEA, //A开启，则nflag为1=0x00000001 TYPEB, //B开启，则nflag为2=0x00000010 TYPEC, //C开启，则nflag为4=0x00000100 TYPED, //D开启，则nflag为8=0x00001000 TYPENUM //枚举最大值，计数用}EMTypeNum;void int2enum (int n){ if(n&(0x01<<TYPEA)) { //为真 cout << "TYPEA is ON\n"; } else { //为假 cout << "TYPEA is OFF\n"; } if(n&(0x01<<TYPEB)) { //为真 cout << "TYPEB is ON\n"; } else { //为假 cout << "TYPEB is OFF\n"; } if(n&(0x01<<TYPEC)) { //为真 cout << "TYPEC is ON\n"; } else { //为假 cout << "TYPEC is OFF\n"; } if(n&(0x01<<TYPED)) { //为真 cout << "TYPED is ON\n"; } else { //为假 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
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原文链接：https://blog.csdn.net/zcc1229936385/article/details/119889252
