学步园

欢迎指正不足

1.c版

int hexcharToInt(char c)
{ 
        if (c >= '0' && c <= '9') return (c - '0');
        if (c >= 'A' && c <= 'F') return (c - 'A' + 10);
        if (c >= 'a' && c <= 'f') return (c - 'a' + 10);
	    return 0;
}

void hexstringToBytes(char* hexstring,char* bytes,int hexlength)
{         
	    cout<<"length is :"<<sizeof(hexstring)/sizeof(char)<<endl;
        for (int i=0 ; i <hexlength ; i+=2) {
            bytes[i/2] = (char) ((hexcharToInt(hexstring[i]) << 4)
                                | hexcharToInt(hexstring[i+1]));
        }
}

void bytesToHexstring(char* bytes,int bytelength,char *hexstring,int hexstrlength)
{
   char str2[16] = {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
   for (int i=0,j=0;i<bytelength,j<hexstrlength;i++,j++) 
   	{
            int b;
            b = 0x0f&(bytes[i]>>4);
            char s1 = str2[b];
	        hexstring[j] = s1;		    
            b = 0x0f & bytes[i];			
	        char s2 = str2[b];
			j++;
            hexstring[j] = s2;	    			
   }
}

int main()
{
   char csh[5] = {'1','2','3','4','\0'};
   cout<<"csh length is :"<<strlen(csh)<<endl;
   char ch[4] = {'1','2','3','4'};
   char str1[8];
   bytesToHexstring(ch,4,str1,8);
   for(int k=0;k<8;k++)
   printf("hex:%x\n",str1[k]);
   char bte[4] ; 
   hexstringToBytes(str1,bte,8);
   for(int m=0;m<4;m++)
   printf("bytes:%x\n",bte[m]);
   return 1;
}

2.c++版

int hexCharToInt(char c)
{ 
        if (c >= '0' && c <= '9') return (c - '0');
        if (c >= 'A' && c <= 'F') return (c - 'A' + 10);
        if (c >= 'a' && c <= 'f') return (c - 'a' + 10);
		return 0;
}

char* hexstringToBytes(string s)
{         
        int sz = s.length();
        char *ret = new char[sz/2];
        for (int i=0 ; i <sz ; i+=2) {
            ret[i/2] = (char) ((hexCharToInt(s.at(i)) << 4)
                                | hexCharToInt(s.at(i+1)));
        }
		return ret;
}

string bytestohexstring(char* bytes,int bytelength)
{
  string str("");
  string str2("0123456789abcdef"); 
   for (int i=0;i<bytelength;i++) {
     int b;
     b = 0x0f&(bytes[i]>>4);
	 char s1 = str2.at(b);
	 str.append(1,str2.at(b));		    
     b = 0x0f & bytes[i];
     str.append(1,str2.at(b));
	 char s2 = str2.at(b);
   }
   return str;
}

int main()
{
   
   char ch[5] ={'1','2','3','4','5'};
   string str = bytestohexstring(ch,5);
   char *chs =new char[5];
   strcpy(chs,str.c_str());
   cout<<endl;
   cout<<str<<endl;
   for(int i = 0;i<10;i++)
   {
      printf("\n%x",chs[i]);
   }
   cout<<endl;
   char* sdf = hexstringToBytes(str);
    for(int j = 0;j<5;j++)
   {
      printf("\n%x",sdf[j]);
   }
   return 1;
}

3.java版

  public int hexCharToInt(char c) {
        if (c >= '0' && c <= '9') return (c - '0');
        if (c >= 'A' && c <= 'F') return (c - 'A' + 10);
        if (c >= 'a' && c <= 'f') return (c - 'a' + 10);
        throw new RuntimeException ("invalid hex char '" + c + "'");
    }

    public byte[]
    hexStringToBytes(String s) {
        byte[] ret;
        if (s == null) return null;
        int sz = s.length();
        ret = new byte[sz/2];
        for (int i=0 ; i <sz ; i+=2) {
            ret[i/2] = (byte) ((hexCharToInt(s.charAt(i)) << 4)
                                | hexCharToInt(s.charAt(i+1)));
        }
        return ret;
    }

    public String
    bytesToHexString(byte[] bytes) {
        if (bytes == null) return null;
        StringBuilder ret = new StringBuilder(2*bytes.length);
        for (int i = 0 ; i < bytes.length ; i++) {
            int b;
            b = 0x0f & (bytes[i] >> 4);
            ret.append("0123456789abcdef".charAt(b));
            b = 0x0f & bytes[i];
            ret.append("0123456789abcdef".charAt(b));
        }
        return ret.toString();
    }