进制转换

//2进制转10进制

• (NSString *)toDecimalSystemWithBinarySystem:(NSString *)binary
  {
  int ll = 0 ;
  int temp = 0 ;
  for (int i = 0; i < binary.length; i ++)
  {
  temp = [[binary substringWithRange:NSMakeRange(i, 1)] intValue];
  temp = temp * powf(2, binary.length - i - 1);
  ll += temp;
  }

  NSString * result = [NSString stringWithFormat:@"%d",ll];

  return result;
  }
  字符串转换16进制
  NSString *hexString = [NSString stringWithFormat:@"%@",[[NSString alloc] initWithFormat:@"%1x",number]];

NSString转char
char mychar[string.length];
strcpy(mychar,(char *)[string UTF8String]);

    char ch = mychar[i];
   原文：http://www.cocoachina.com/bbs/read.php?tid=141348

/将十进制转化为二进制,设置返回NSString 长度

• (NSString *)decimalTOBinary:(uint16_t)tmpid backLength:(int)length
  {
  NSString *a = @"";
  while (tmpid)
  {
  a = [[NSString stringWithFormat:@"%d",tmpid%2] stringByAppendingString:a];
  if (tmpid/2 < 1)
  {
  break;
  }
  tmpid = tmpid/2 ;
  }

  if (a.length <= length)
  {
  NSMutableString *b = [[NSMutableString alloc]init];;
  for (int i = 0; i < length - a.length; i++)
  {
  [b appendString:@"0"];
  }

    a = [b stringByAppendingString:a];
    [b release];
  

  }

  return a;

}

//将十进制转化为十六进制

• (NSString *)ToHex:(uint16_t)tmpid
  {
  NSString *nLetterValue;
  NSString *str =@"";
  uint16_t ttmpig;
  for (int i = 0; i<9; i++) {
  ttmpig=tmpid%16;
  tmpid=tmpid/16;
  switch (ttmpig)
  {
  case 10:
  nLetterValue =@"A";break;
  case 11:
  nLetterValue =@"B";break;
  case 12:
  nLetterValue =@"C";break;
  case 13:
  nLetterValue =@"D";break;
  case 14:
  nLetterValue =@"E";break;
  case 15:
  nLetterValue =@"F";break;
  default:
  nLetterValue = [NSString stringWithFormat:@"%u",ttmpig];

    }
    str = [nLetterValue stringByAppendingString:str];
    if (tmpid == 0) {
        break;
    }
  

  }
  return str;
  }
  //将16进制转化为二进制

-(NSString *)getBinaryByhex:(NSString *)hex
{
NSMutableDictionary *hexDic = [[NSMutableDictionary alloc] init];

hexDic = [[NSMutableDictionary alloc] initWithCapacity:16];
 
[hexDic setObject:@"0000" forKey:@"0"];
 
[hexDic setObject:@"0001" forKey:@"1"];
 
[hexDic setObject:@"0010" forKey:@"2"];
 
[hexDic setObject:@"0011" forKey:@"3"];
 
[hexDic setObject:@"0100" forKey:@"4"];
 
[hexDic setObject:@"0101" forKey:@"5"];
 
[hexDic setObject:@"0110" forKey:@"6"];
 
[hexDic setObject:@"0111" forKey:@"7"];
 
[hexDic setObject:@"1000" forKey:@"8"];
 
[hexDic setObject:@"1001" forKey:@"9"];
 
[hexDic setObject:@"1010" forKey:@"A"];
 
[hexDic setObject:@"1011" forKey:@"B"];
 
[hexDic setObject:@"1100" forKey:@"C"];
 
[hexDic setObject:@"1101" forKey:@"D"];
 
[hexDic setObject:@"1110" forKey:@"E"];
 
[hexDic setObject:@"1111" forKey:@"F"];
 
NSMutableString *binaryString=[[NSMutableString alloc] init];
 
for (int i=0; i<[hex length]; i++) {
     
    NSRange rage;
     
    rage.length = 1;
     
    rage.location = i;
     
    NSString *key = [hex substringWithRange:rage];
     
    //NSLog(@"%@",[NSString stringWithFormat:@"%@",[hexDic objectForKey:key]]);
     
    binaryString = [NSString stringWithFormat:@"%@%@",binaryString,[NSString stringWithFormat:@"%@",[hexDic objectForKey:key]]];
     
}
 
//NSLog(@"转化后的二进制为:%@",binaryString);
 
return binaryString;

}