普通字符串和Hex字符串转换

      写了个普通字符串和Hex字符串转换函数，权当练练手吧

 

#include <string.h>

//将普通字符串转化成Hex字符串
void str2hex(char* str, char* hex)
{

    const char* cHex = "0123456789ABCDEF";
    int i=0;
    for(int j =0; j < strlen(str); j++)
    {
        unsigned int a =  (unsigned int) str[j];
        hex[i++] = cHex[(a & 0xf0) >> 4];
        hex[i++] = cHex[(a & 0x0f)];
    }
    hex[i] = '\0';
}
//将Hex字符串转换成普通字符串
void hex2str(char* hex,char* str)
{

    int i=0;
    for(int j =0; j < strlen(hex) -1; )
    {
        unsigned int a =  hex2int(hex[j++]);
        unsigned int b =  hex2int(hex[j++]);
        str[i++] = char(a *16 + b);
    }
    str[i] = '\0';
}
//将Hex字符转换成无符号整型
unsigned int hex2int(char c)
{
    if( c >= '0' && c <= '9')
    {
        return (unsigned int) (c -48);
    }
    else if( c >= 'A' && c <= 'B')
    {
        return (unsigned int) (c -65);
    }
    else if( c >= 'a' && c <= 'b')
    {
        return (unsigned int) (c - 97);
    }
    else
    {
        return 0;
    }
}