Objective-C的NSString for循环与characterAtIndex [英] Objective-C NSString for loop with characterAtIndex

问题描述

我试图循环遍历一个字符的NSString，但是我得到一个EXC_BAD_ACCESS错误。你有一个想法如何做到这一点？我已经搜索了几个小时，但无法弄清楚。

这是我的代码（.m）：

  self.textLength = [self.text length]; 
 
（int position = 0; position< self.textLength; position ++）{
 
 NSLog（@％@，[self.text characterAtIndex：position]） ; 
 
 if（[[self.text characterAtIndex：position] isEqualToString：@。]）{
 NSLog（@it's a。）; 
 
 
 
 
 $ b $ p $非常感谢！
 
解决方案
字符不是对象。  characterAtIndex 返回 unichar ，它实际上是一个整数类型 unsigned short 。您需要在 NSLog 中使用％C ，而不是％@  >。而且字符不是 NSString ，所以你不能发送 isEqualToString 。你需要使用 ch =='。'来比较 ch 和'。'。
  unichar ch = [self.text characterAtIndex：position]; 
 NSLog（@％C，ch）; 
 
 if（ch =='。'）{} //单引号，而不是双引号
  
请注意，'a'是字符，a是C字符串，  @a是NSString。它们都是不同的类型。
 
 
 
当您使用％@  with unichar  ch 在 NSLog 中，它试图从内存位置 ch 打印一个无效的对象。因此你得到一个EXC_BAD_ACCESS。
 
I'm trying to loop through a NSString, character by character, but I'm getting a EXC_BAD_ACCESS error. Do you have an idea how to do this right? I've been googling for hours now but can't figure it out.

Here is my code (.m):
self.textLength = [self.text length];

for (int position=0; position < self.textLength; position++) {

    NSLog(@"%@", [self.text characterAtIndex:position]);

    if ([[self.text characterAtIndex:position] isEqualToString:@"."]){
        NSLog(@"it's a .");
    }
}
Thanks a lot!
解决方案
Characters are not object. characterAtIndex returns unichar, which is actually an integer type unsigned short. You need to use %C instead of %@ in NSLog. Also character is not a NSString, so you can't send it isEqualToString. You need to use ch == '.' to compare ch against '.'.
unichar ch = [self.text characterAtIndex:position];
NSLog(@"%C", ch);

if (ch == '.') {} // single quotes around dot, not double quotes
Note that, 'a' is character, "a" is C string and @"a" is NSString. They all are different types.

When you are using %@ with unichar ch in NSLog, it is trying to print an object from memory location ch which is invalid. Thus you are getting a EXC_BAD_ACCESS.

                        
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