C/C++(int数与多枚举值互转的实现)

C/C++,int数与多枚举值互转的实现，久久派带你了解更多相关信息。

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:

#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 OFF

nFlag:3
TYPEA is ON
TYPEB is ON
TYPEC is OFF
TYPED is OFF

nFlag:7
TYPEA is ON
TYPEB is ON
TYPEC is ON
TYPED is OFF

nFlag:15
TYPEA is ON
TYPEB is ON
TYPEC is ON
TYPED is ON

nFlag:14
TYPEA is OFF
TYPEB is ON
TYPEC is ON
TYPED is ON

nFlag:12
TYPEA is OFF
TYPEB is OFF
TYPEC is ON
TYPED is ON

nFlag:8
TYPEA is OFF
TYPEB is OFF
TYPEC is OFF
TYPED is ON

nFlag:0
TYPEA is OFF
TYPEB is OFF
TYPEC is OFF
TYPED is OFF

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