我试图解决problem 22 from Project Euler,用下面的代码:奇怪溢出 - Objective-C的
NSArray *alphabet = [NSArray arrayWithObjects:@"A",@"B",@"C",@"D",@"E",@"F",@"G",@"H",@"I",@"J",@"K",@"L",@"M",@"N",@"O",@"P",@"Q",@"S",@"T",@"U",@"V",@"W",@"X",@"Y",@"Z",nil];
NSError *error = nil;
NSString *file = [[NSBundle mainBundle] pathForResource:@"names" ofType:@"txt"];
NSString *names = [[NSString alloc] initWithContentsOfFile: file
encoding: NSASCIIStringEncoding
error: &error];
if (names == nil) {
[NSException raise:@"Error reading file :" format:@"%@",error];
}
NSMutableArray *namesArray = [NSMutableArray arrayWithArray:[names componentsSeparatedByString:@","]];
unsigned long long int sum = 0;
unsigned long long int partSum = 0;
for (NSString *str in namesArray){
partSum = 0;
for (int i = 0; i < [str length]; i++) {
partSum += [alphabet indexOfObject:[NSString stringWithFormat:@"%c",[str characterAtIndex:i]]]+1;
NSLog(@"%lli",partSum);
}
NSLog(@"%@ - %lli",str,partSum);
sum += [namesArray indexOfObject:str]*partSum;
}
NSLog(@"%lli",sum);
没有关于获取名称为数组,但问题,当我登录了sum
和partSum
变量我得到奇怪的值,如-9223372036854775755
。据我所知,这是由于溢出,但是当程序计算的实例名称看,我得到以下的输出:
-9223372036854775808
-9223372036854775805
-9223372036854775790
-9223372036854775778
-9223372036854775769
-9223372036854775755
53
"COLIN" - 53
第一值然泪下,但最后的结果是奇怪的是正确的(不是所有名字的情况)。为什么这样的溢出?这些数字应该只是3,18,30,39,53。猜测应该是该程序还会处理"
字符,并在alphabet
中寻找索引。为此,我在网上看了很多,找不到如何从字符串中删除它们。我不能只使用[str stringByReplacingOccurrencesOfString:@""" withString:@""]
。有什么建议么?
谢谢您的回答,但处理它,但不删除'“单曲。 – user2331955 2013-05-05 00:26:18