范围超出界限的子串？ [英] Substring with range out of bounds?

问题描述

好的，所以这有点令人困惑（对我而言）。我有一个字符串，它有一个我想要的数字。我已经用'/'包围了这个数字，这样我以后就能从中得到这个数字。

Okay, so this is a bit confusing (well to me). I have a string that has a single number I want out of it. I have surrounded this number with '/' so that I will be able to get that number out of it later.

这是我如何得到它的数字：

Here is how I am getting the number out of it:

if ([MYSTRING hasSuffix:@"mp"]) {
        int start = 0;
        int end = 0;
        char looking = '/';
        for(int i=0; i < MYSTRING.length; i++){
            if (looking == [MYSTRING characterAtIndex:i]) {
                if (start == 0) {
                    start = i;
                }
                else{
                    end = i + 1;
                }
            }
        }
        NSLog(@"%@", MYSTRING); //When i NSLOG here i get '2012-06-21 03:58:00 +0000/1/mp', 1 is the number i want out of the string, but this number could also change to 55 or whatever the user has
        NSLog(@"start: %i, end: %i", start, end); //When i NSLOG here i get 'start: 25, end: 28'
        NSString *number = [MYSTRING substringWithRange:NSMakeRange(start, end)];
        number = [number stringByReplacingOccurrencesOfString:@"/" withString:@""];
        if ([number intValue] > numberInt) {
            numberInt = [number intValue];
        }

它一直崩溃，控制台说：

It keeps crashing and the console says:

<强> *终止应用程序由于未捕获的异常 'NSRangeException'，原因： ' - [__ NSCFString substringWithRange：]：范围或索引超出范围'
*的首先掷调用堆栈：
（0x1875d72 0x106ce51 0x1875b4b 0x184ea64 0x3a6c 0x1080713 0x1bf59 0x1bef1 0xd532e 0xd588c 0xd49f5 0x49a2f 0x49c42 0x290fe 0x1b3fd 0x17d2f39 0x17d2c10 0x17ebda5 0x17ebb12 0x181cb46 0x181bed4 0x181bdab 0x17d1923 0x17d17a​​8 0x18e71 0x200d 0x1f35）
的libc ++ ABI .dylib：终止调用抛出异常

* Terminating app due to uncaught exception 'NSRangeException', reason: '-[__NSCFString substringWithRange:]: Range or index out of bounds' * First throw call stack: (0x1875d72 0x106ce51 0x1875b4b 0x184ea64 0x3a6c 0x1080713 0x1bf59 0x1bef1 0xd532e 0xd588c 0xd49f5 0x49a2f 0x49c42 0x290fe 0x1b3fd 0x17d2f39 0x17d2c10 0x17ebda5 0x17ebb12 0x181cb46 0x181bed4 0x181bdab 0x17d1923 0x17d17a8 0x18e71 0x200d 0x1f35) libc++abi.dylib: terminate called throwing an exception

从我的计算范围是在范围内，我不知道为什么我得到这个错误？

From my counting the range is within the bounds, I dont get why I am getting this error?

任何帮助都将不胜感激。

Any help would be appreciated.

谢谢

推荐答案

你的NSMakeRange（开始，结束）应该是NSMakeRange（开始，结束 - 开始）;

Your NSMakeRange(start, end) should be NSMakeRange(start, end- start);

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