OC中NSString字符串操作知识点归纳

 

NSString类常用函数大总结

 

#import

main(int argc, const char * argv[]) {

    @autoreleasepool {

        NSString *str = @"helloworld";

        //求字符串长度

        NSInteger len = [str length];

        NSLog(@"len = %li", len);

        //获取指定位置的字符

        unichar ch = [str characterAtIndex:10];

        NSLog(@"ch = %C", ch);//打印OC中的字符用%C

        

        //从指定位置提取子串到字符串结束

        NSString *subStr1 = [str substringFromIndex:5];

        NSLog(@"subStr1 = %@", subStr1);

        //提取子串到指定位置(不包含传入位置的字符)

        NSString *subStr2 = [str substringToIndex:5];

        NSLog(@"subStr2 = %@", subStr2);

        //提取指定范围的字符串

        NSRange range = {5,5};

        NSString *subStr3 = [str substringWithRange:range];

        NSLog(@"subStr3 = %@", subStr3);

        NSString *subStr4 = [str substringWithRange:NSMakeRange(10, 2)];

        NSLog(@"subStr4 = %@", subStr4);

        //字符串比较

        //- (NSComparisonResult)compare:(NSString *)aString;

        

        NSString *str1 = @"helloworld";

        NSString *str2 = @"helloworld";

        //大小写不敏感方式比较字符串对象

        //返回值:NSOrderedAscending = -1: 递增顺序 str1 < str2

        //NSOrderedSame: 相等   str1==str2

        //NSOrderedDescending: 递减顺序  str1>str2

        NSComparisonResult ret = [str1 caseInsensitiveCompare:str2];

        NSLog(@"ret = %li", ret);

        

        //判断两个字符串对象是否相等

        BOOL ret1 = [str1 isEqualTo:str2];

        NSLog(@"ret1 = %i", ret1);

        //判断是否包含前缀子串

        BOOL ret2 = [@"www.baidu.com" hasPrefix:@"www"];

        NSLog(@"ret2 = %i", ret2);

        

        //判断是否包含后缀子串

        BOOL ret3 = [@"www.baidu.com" hasSuffix:@"com"];

        NSLog(@"ret3 = %i", ret3);

    

        //查找子串

        NSString *str3 = @"www.hao123hao.com";

        NSRange range1 = [str3 rangeOfString:@"hao"];//返回long类型范围最大值

        if (range1.location==NSNotFound) {

            NSLog(@"没有找到该子串 %lu", NSNotFound);

        }

        else

        {

            NSLog(@"location = %lu, length = %lu", range1.location, range1.length);

        }

        

        //倒序查找子串

        NSRange range2 = [str3 rangeOfString:@"hao" options:NSBackwardsSearch];

        if (range2.location == NSNotFound) {

            NSLog(@"没有找到该子串");

        }

        else

        {

            NSLog(@"location = %lu, length = %lu", range2.location, range2.length);

        }

        //返回字符集合中的字符第一次在原字符串对象中出现的位置

        NSRange range3 = [@"helloworld" rangeOfCharacterFromSet:[NSCharacterSet characterSetWithCharactersInString:@"lo"]];

        NSLog(@"location = %li length = %li", range3.location, range3.length);

        //字符串追加

        NSString *str4= @"hello";

        NSString *str5 = [str4 stringByAppendingString:@"world"];

        NSLog(@"str5 = %@", str5);

        NSLog(@"str4 = %@", str4);

        NSLog(@"str4 = %p str5 = %p", str4, str5);

        //格式化追加字符串

        NSString *str6 = [str4 stringByAppendingFormat:@"%s%d","world",567];

        NSLog(@"str6 = %@", str6);

        //把数字字符串转换成数字

        float f = [@"3.56" floatValue];

        int num= [@"8765" intValue];

        NSInteger val = [@"098765" integerValue];

        NSLog(@"f = %.2f num = %i val = %li", f, num, val);

        

        //大小写转换

        NSLog(@"%@", [@"qianfeng中国" uppercaseString]);//把小写字母转换成大写字母

        NSLog(@"%@", [@"HELLOworld" lowercaseString]);//把大写字母转换成小写字母

        NSLog(@"%@", [@"hello WORLD qianfeng" capitalizedString]);//每个单词的首字母大写,其余字母小写

        //字符串替换

        //用给定的字符串替换所有在原字符串中出现的目标字符串

        NSString *str7 = [NSString stringWithUTF8String:"helloworldhelloqianhellofeng"];

        NSString *str8 = [str7 stringByReplacingOccurrencesOfString:@"hello"withString:@"中国"];

        NSLog(@"str8 = %@", str8);

        //用给定的字符串对象替换指定范围内的字符

        NSString *str9 = [str7 stringByReplacingCharactersInRange:NSMakeRange(5, 10)withString:@"千锋"];

        NSLog(@"str9 = %@", str9);

        //把OC字符串对象转换成C语言字符串

        NSLog(@"%s", [@"helloworld" UTF8String]);

        

        //返回公共前缀子串

        NSString *str10 = @"helloworldqianfeng";

        NSString *str11 = @"hellofengqian";

        NSString *str12 = [str10 commonPrefixWithString:str11 options:NSLiteralSearch];

        NSLog(@"str12=%@", str12);

    }

    return 0;

}