（轉）【iOS 開發】二進位制、十進位制、十六進位制相互轉換的方法

七仔已成仙發表於2017-12-13
iOS

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下面羅列了二進位制、十進位制、十六進位制之間相互轉換的方法，有時候可能會用的到，需要的朋友可以收藏一下。

###1. 十進位制轉換為二進位制

/**
 十進位制轉換為二進位制

 @param decimal 十進位制數
 @return 二進位制數
 */
+ (NSString *)getBinaryByDecimal:(NSInteger)decimal {

    NSString *binary = @"";
    while (decimal) {

        binary = [[NSString stringWithFormat:@"%ld", decimal % 2] stringByAppendingString:binary];
        if (decimal / 2 < 1) {

            break;
        }
        decimal = decimal / 2 ;
    }
    if (binary.length % 4 != 0) {

        NSMutableString *mStr = [[NSMutableString alloc]init];;
        for (int i = 0; i < 4 - binary.length % 4; i++) {

            [mStr appendString:@"0"];
        }
        binary = [mStr stringByAppendingString:binary];
    }
    return binary;
}
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###2. 十進位制轉換為十六進位制

/**
 十進位制轉換十六進位制

 @param decimal 十進位制數
 @return 十六進位制數
 */
+ (NSString *)getHexByDecimal:(NSInteger)decimal {

    NSString *hex =@"";
    NSString *letter;
    NSInteger number;
    for (int i = 0; i<9; i++) {

        number = decimal % 16;
        decimal = decimal / 16;
        switch (number) {

            case 10:
                letter =@"A"; break;
            case 11:
                letter =@"B"; break;
            case 12:
                letter =@"C"; break;
            case 13:
                letter =@"D"; break;
            case 14:
                letter =@"E"; break;
            case 15:
                letter =@"F"; break;
            default:
                letter = [NSString stringWithFormat:@"%ld", number];
        }
        hex = [letter stringByAppendingString:hex];
        if (decimal == 0) {

            break;
        }
    }
    return hex;
}
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###3. 二進位制轉換為十六進位制

/**
 二進位制轉換成十六進位制

 @param binary 二進位制數
 @return 十六進位制數
 */
+ (NSString *)getHexByBinary:(NSString *)binary {

    NSMutableDictionary *binaryDic = [[NSMutableDictionary alloc] initWithCapacity:16];
    [binaryDic setObject:@"0" forKey:@"0000"];
    [binaryDic setObject:@"1" forKey:@"0001"];
    [binaryDic setObject:@"2" forKey:@"0010"];
    [binaryDic setObject:@"3" forKey:@"0011"];
    [binaryDic setObject:@"4" forKey:@"0100"];
    [binaryDic setObject:@"5" forKey:@"0101"];
    [binaryDic setObject:@"6" forKey:@"0110"];
    [binaryDic setObject:@"7" forKey:@"0111"];
    [binaryDic setObject:@"8" forKey:@"1000"];
    [binaryDic setObject:@"9" forKey:@"1001"];
    [binaryDic setObject:@"A" forKey:@"1010"];
    [binaryDic setObject:@"B" forKey:@"1011"];
    [binaryDic setObject:@"C" forKey:@"1100"];
    [binaryDic setObject:@"D" forKey:@"1101"];
    [binaryDic setObject:@"E" forKey:@"1110"];
    [binaryDic setObject:@"F" forKey:@"1111"];

    if (binary.length % 4 != 0) {

        NSMutableString *mStr = [[NSMutableString alloc]init];;
        for (int i = 0; i < 4 - binary.length % 4; i++) {

            [mStr appendString:@"0"];
        }
        binary = [mStr stringByAppendingString:binary];
    }
    NSString *hex = @"";
    for (int i=0; i<binary.length; i+=4) {

        NSString *key = [binary substringWithRange:NSMakeRange(i, 4)];
        NSString *value = [binaryDic objectForKey:key];
        if (value) {

            hex = [hex stringByAppendingString:value];
        }
    }
    return hex;
}
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###4. 十六進位制轉換為二進位制

/**
 十六進位制轉換為二進位制

 @param hex 十六進位制數
 @return 二進位制數
 */
+ (NSString *)getBinaryByHex:(NSString *)hex {

    NSMutableDictionary *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"];

    NSString *binary = @"";
    for (int i=0; i<[hex length]; i++) {

        NSString *key = [hex substringWithRange:NSMakeRange(i, 1)];
        NSString *value = [hexDic objectForKey:key.uppercaseString];
        if (value) {

            binary = [binary stringByAppendingString:value];
        }
    }
    return binary;
}
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###5. 二進位制轉換為十進位制

/**
 二進位制轉換為十進位制

 @param binary 二進位制數
 @return 十進位制數
 */
+ (NSInteger)getDecimalByBinary:(NSString *)binary {

    NSInteger decimal = 0;
    for (int i=0; i<binary.length; i++) {

        NSString *number = [binary substringWithRange:NSMakeRange(binary.length - i - 1, 1)];
        if ([number isEqualToString:@"1"]) {

            decimal += pow(2, i);
        }
    }
    return decimal;
}
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大概就這麼多了，有其他需求可以補充，需要十六進位制轉換為十進位制的話，就按上面方法將十六進位制轉換為二進位制後再轉換為十進位制就行了，有需要的朋友就收藏一下吧！

http://www.jianshu.com/p/126ebfbd460e

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