OC中常用的字符处理

NSString *str1 = @"BeiJing";  
   NSString *str2 = @"beijing";  
     
   //全部转为大写  
   NSLog(@"%@",[str1 uppercaseString]);  
     
   //全部转为小写  
   NSLog(@"%@",[str1 lowercaseString]);  
     
   //首字母大写  
   NSLog(@"%@",[str1 capitalizedString]);  
     
   //比较两个字符串内容是否相同  
   BOOL b =[str1 isEqualToString:str2];  
     
   //两个字符串内容比较  
   //NSOrderedAscending    右边 > 左边  
   //NSOrderedSame         内容相同  
   //NSOrderedDescending   左边 > 右边  
   NSComparisonResult result = [str1 compare:str2];  
   if (result == NSOrderedAscending) {  
       NSLog(@"右边 > 左边");  
   }else if(result == NSOrderedSame){  
       NSLog(@"内容相同");  
   }else if (result == NSOrderedDescending){  
       NSLog(@"左边 > 右边");  
   }  
     
   //忽略大小写进行比较，返回值与compare一样  
   result = [str1 caseInsensitiveCompare:str2];  
   if (result == NSOrderedAscending) {  
       NSLog(@"右边 > 左边");  
   }else if(result == NSOrderedSame){  
       NSLog(@"内容相同");  
   }else if (result == NSOrderedDescending){  
       NSLog(@"左边 > 右边");  
   }  
     
   //判断字符串是否以指定字符串开头  
   [str1 hasPrefix:@"aaa"];  
   //判断字符串是否以指定字符串结尾  
   [str1 hasSuffix:@"aaa"];  
     
   //判断字符串是否包含指定字符串，返回位置和长度  
   NSRange range = [@"123456" rangeOfString:@"456"];  
   NSLog(@"%@", NSStringFromRange(range));  
     
   //反向搜索  
   range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch];  
   NSLog(@"%@",NSStringFromRange(range));  
     
   //指定范围进行搜索  
   range = NSMakeRange(0, 9);  
   range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch range:range];  
   NSLog(@"%@",NSStringFromRange(range));  

<pre name="code" class="cpp">//字符串的截取  
        NSString *str = @"123456789";  
        NSLog(@"%@",[str substringFromIndex:3]);  
        NSLog(@"%@",[str substringToIndex:6]);  
        NSLog(@"%@",[str substringWithRange:NSMakeRange(3, 3)]);  
          
        //用指定字符串分割字符串，返回一个数组  
        NSArray *array = [@"1,2,3,4,5,6" componentsSeparatedByString:@","];  
        NSLog(@"%@",array);  
          
        //将数组中的字符串组合成一个文件路径  
        NSMutableArray *components = [NSMutableArray array];  
        [components addObject:@"Users"];  
        [components addObject:@"CentralPerk"];  
        [components addObject:@"Desktop"];  
        NSString *path = [NSString pathWithComponents:components];  
        NSLog(@"%@",path);  //Users/CentralPerk/Desktop  
          
        //将一个路径分割成一个数组  
        NSArray *array1 = [path pathComponents];  
        NSLog(@"%@",array1);  
          
        //判断是否为绝对路径(依据：是否以'/'开始)  
        path = @"/Users/CentralPerk/Desktop";  
        NSLog(@"%i",[path isAbsolutePath]);  
          
        //获取最后一个目录  
        NSLog(@"%@",[path lastPathComponent]);  
          
        //删除最后一个目录  
        NSLog(@"%@",[path stringByDeletingLastPathComponent]);  
          
        //拼接一个目录  
        NSLog(@"%@",[path stringByAppendingPathComponent:@"aaa"]);   ///Users/CentralPerk/Desktop/aaa  
        NSLog(@"%@",[path stringByAppendingString:@"aaa"]);      ///Users/CentralPerk/Desktopaaa  
        NSLog(@"%@",[path stringByAppendingFormat:@"%@%@",@"b",@"c"]);  ///Users/CentralPerk/Desktopbc  
          
        //拓展名出来  
        //获取拓展名,不带.  
        NSString *str2 = @"Users/CentralPerk/Desktop/test.txt";  
        NSLog(@"%@",[str2 pathExtension]);  
        //添加拓展名,不需要带.  
        NSLog(@"%@",[str2 stringByAppendingPathExtension:@"mp3"]);  
        //删除拓展名,带.一块删除  
        NSLog(@"%@",[str2 stringByDeletingPathExtension]);  
          
        //字符串转为 int double float  
        NSString *str3 = @"123";  
        NSLog(@"%i",[str3 intValue]);  
        NSLog(@"%zi",[str3 length]);  
          
        //取出指定位置的字符  
        unichar c = [str3 characterAtIndex:2];  
        NSLog(@"%c",c);  
          
        //转为C语言的字符串  
        const char *s = [str3 UTF8String];  
        NSLog(@"%s",s);  
</pre><br><br>