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>