面试题-字符串转字典

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昨天面试的时候遇到一道字符串转字典的题，当时把思路写了下来，今天用代码实现一下。

题目的内容大致是这样：

把一个字符串如：afh123jkkx2324klsdkjl839283a3b323n，取出字母作为key,数字作为value，存入一个字典。

由于字符串的内容只有字母和数字，所以我的大致思路是遍历字符串，判断每个字符的ASCII码，0-9的ASCII码是48~57。在每次字母和数字切换的位置标记为分割点，然后依次取出key，value.
下面用两种方式实现

第一种

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- (void) stringToDic:(NSString *)string {
    
    NSMutableDictionary *dic = [NSMutableDictionary dictionary];
    BOOL isNumber = YES;
    NSInteger startPoint = 0;//记录开始点
    NSString *tempKey = @"";
    NSString *tempValue = @"";
    for (NSInteger i=0; i< string.length; i++) {
        
        unichar charStr = [string characterAtIndex:i];
        int ascii = toascii(charStr);//获取ASCII码
        //判断key和value都不为空，保存到dic
        if (![tempKey isEqualToString:@""] && ![tempValue isEqualToString:@""]) {
            [dic setObject:tempValue forKey:tempKey];
            tempKey = @"";
            tempValue = @"";
        }
        if (ascii>=48 && ascii <= 57) {//数字
            if (isNumber == NO) {
                tempKey = [string substringWithRange:NSMakeRange(startPoint, i-startPoint)];
                startPoint = i;
                isNumber = YES;
            }
        }else{//字母
            if (isNumber == YES) {
                tempValue = [string substringWithRange:NSMakeRange(startPoint, i-startPoint)];
                startPoint = i;
                isNumber = NO;
            }
        }
        if(i == string.length -1){//最后一个单独处理
            if (![tempKey isEqualToString:@""] && ![tempValue isEqualToString:@""]) {
                [dic setObject:tempValue forKey:tempKey];
            }
        }
    }
    NSLog(@"%@",dic);
}

目标字符串：afh123jkkx2324klsdkjl839283a3b323n
打印结果 

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{
    a = 3;
    afh = 123;
    b = 323;
    jkkx = 2324;
    klsdkjl = 839283;
}

第二种

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- (void) stringToDictionary:(NSString *)string {
    
    NSMutableArray *array = [NSMutableArray array];
    NSMutableDictionary *dic = [NSMutableDictionary dictionary];
    BOOL isNumber = YES;
    for (NSInteger i=0; i< string.length; i++) {
        
        unichar charStr = [string characterAtIndex:i];
        int ascii = toascii(charStr);
        
        if (ascii>=48 && ascii <= 57) {//数字
            if (isNumber == NO) {
                isNumber = YES;
                [array addObject:@(i)];
            }
            
            
        }else{//字母
            if (isNumber == YES) {
                isNumber = NO;
                [array addObject:@(i)];
            }
        }
    }
    
    //最后一个单独处理
    [array addObject:@(string.length)];
    //根据分割点切割成字母和数字存入零时数组
    NSMutableArray *keyValues = [NSMutableArray array];
    for (NSInteger i = 0; i < array.count-1; i++) {
        NSInteger start = [array[i] integerValue];
        NSInteger lengt = [array[i+1] integerValue] -start;
        NSString *itemStr = [string substringWithRange:NSMakeRange(start, lengt)];
        [keyValues addObject:itemStr];
    }
    NSLog(@"%@",keyValues);
    //从数组中取出元素存入字典，循环的步数为2
    for (NSInteger i = 0; i<keyValues.count-1; i=i+2) {
        NSString *key = keyValues[i];
        NSString *value = keyValues[i+1];
        [dic setObject:value forKey:key];
    }
    NSLog(@"%@",dic);
}

目标字符串：afh123jkkx2324klsdkjl839283a3b323n
打印结果 

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2018-07-26 12:41:03.921236+0800 Demo[42540:6832719] (
    afh,
    123,
    jkkx,
    2324,
    klsdkjl,
    839283,
    a,
    3,
    b,
    323,
    n
)
2018-07-26 12:41:03.921494+0800 Demo[42540:6832719] {
    a = 3;
    afh = 123;
    b = 323;
    jkkx = 2324;
    klsdkjl = 839283;
}

注意

这里需要注意的是字母和数字可能不是成对出现，那么需要处理异常情况，这里只是处理了结束位置为字母的情况，还有一种开始位置为数字的情况没有讨论。