ios 字符串

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/*----------------比较两个字符串----------------*/

   //用C比较:strcmp函数

   char string1[] = "string!";
   char string2[] = "string!";
   if(strcmp(string1, string2) = = 0)
   {
        NSLog(@"1");
   }



   //isEqualToString方法
   NSString *astring01 = @"This is a String!";
   NSString *astring02 = @"This is a String!";
   BOOL result = [astring01 isEqualToString:astring02];
   NSLog(@"result:%d",result);




   //compare方法(comparer返回的三种值)
   NSString *astring01 = @"This is a String!";
   NSString *astring02 = @"This is a String!";
   BOOL result = [astring01 compare:astring02] = = NSOrderedSame;
   NSLog(@"result:%d",result);
   //NSOrderedSame判断两者内容是否相同




   NSString *astring01 = @"This is a String!";
   NSString *astring02 = @"this is a String!";
   BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;
   NSLog(@"result:%d",result);
   //NSOrderedAscending判断两对象值的大小(按字母顺序进行比较，astring02大于astring01为真)



   NSString *astring01 = @"this is a String!";
   NSString *astring02 = @"This is a String!";
   BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;
   NSLog(@"result:%d",result);
   //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)



   //不考虑大小写比较字符串1
   NSString *astring01 = @"this is a String!";
   NSString *astring02 = @"This is a String!";
   BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;
   NSLog(@"result:%d",result);
   //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)



   //不考虑大小写比较字符串2
   NSString *astring01 = @"this is a String!";
   NSString *astring02 = @"This is a String!";
   BOOL result = [astring01 compare:astring02
                            options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;
   NSLog(@"result:%d",result);

//NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较，区分大小写 NSNumericSearch:比较字符串的字符个数，而不是字符值。

/*-------------判断字符串内是否还包含别的字符串(前缀，后缀)-------------*/
   //01：检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString *) aString;
   NSString *String1 = @"NSStringInformation.txt";
   [String1 hasPrefix:@"NSString"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");
   [String1 hasSuffix:@".txt"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");

/*---------------------------切分数组------------------------------*/

   //从字符串分割到数组－ componentsSeparatedByString:
   NSString *string = [[NSString alloc] initWithString:@"One,Two,Three,Four"];
   NSLog(@"string:%@",string);
   NSArray *array = [string componentsSeparatedByString:@","];
   NSLog(@"array:%@",array);

  //从数组合并元素到字符串- componentsJoinedByString:
   NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
   NSString *string = [array componentsJoinedByString:@","];

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