进制转换

//反转字符串

+ (NSString*)fanZhuan:(NSString*)str{

unsignedlonglen;

len = [strlength];

unichara[len];

for(inti =0; i < len; i++)

{

unicharc = [strcharacterAtIndex:len-i-1];

a[i] = c;

}

return[NSStringstringWithCharacters:alength:len];

}

//十进制转二进制

+ (NSString*)toBinarySystemWithDecimalSystem:(NSString*)decimal With:(int)length

{

NSString* temStr =@"";

NSString* result =@"";

intnum = [decimalintValue];

intremainder =0;//余数

intdivisor =0;//除数

while(true)

{

remainder = num%2;

divisor = num/2;

num = divisor;

temStr = [temStrstringByAppendingFormat:@"%d",remainder];

if(divisor ==0)

{

break;

}

}

for(inti = (int)(temStr.length-1); i >=0; i --)

{

result = [resultstringByAppendingFormat:@"%@",

[temStrsubstringWithRange:NSMakeRange(i ,1)]];

}

if(result.length<= length)

{

NSMutableString*b = [[NSMutableStringalloc]init];;

for(inti =0; i < length - result.length; i++)

{

[bappendString:@"0"];

}

return[selffanZhuan:[bstringByAppendingString:result]];

}

else

{

return[selffanZhuan:result];

}

}

//二进制转十进制

+ (NSString*)toDecimalSystemWithBinarySystem:(NSString*)binary

{

NSString* temStr = [selffanZhuan:binary];

intll =0;

inttemp =0;

for(inti =0; i < temStr.length; i ++)

{

temp = [[temStrsubstringWithRange:NSMakeRange(i,1)]intValue];

temp = temp *powf(2, temStr.length- i -1);

ll += temp;

}

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

returnresult;

}