目标C ..中的可变字符串初始化问题 [英] mutable string initialization problem in Objective C ..
本文介绍了目标C ..中的可变字符串初始化问题的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
int main (int argc, const char * argv[])
{
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
NSMutableString *str1;
[str1 setString:@"again"];
NSLog(@"string is -- %@",str1); // It prints " string is -- (null) "
[str1 release];
[pool drain];
return 0;
}
-------------------------------------------------- ----------------------------------
------------------------------------------------------------------------------------
int main (int argc, const char * argv[])
{
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
NSMutableString *str1;
str1 = [NSMutableString stringWithString:@"hello again "]; // By adding this
[str1 setString:@"again"]; // Now this statements works properly .
NSLog(@"string is -- %@",str1);
[str1 release];
[pool drain];
return 0;
}
我不明白为什么如果我先使用setString
方法,str1没有初始化?
I can not understand why if I use setString
method first, str1 is not initializing??
推荐答案
别忘了初始化NSMutableString
NSMutableString * str1 = [[NSMutableString alloc] init];
Don''t forget init NSMutableString
NSMutableString *str1 = [[NSMutableString alloc]init];
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