字符串

 

//C语言字符串

//1.每个字符占用一个字节空间

//2.字符串以'\0'结束

//3.字符串用""包含

//4.打印字符串用%s

//5.字符串中的每个字符以ASCII码形式存储

 

//字符串对象

//1.用@" "包含表示是一个字符串对象

//2.字符串对象中的每个字符占用空间大小不确定

//3.字符以UTF-8编码形式存储,UTF-8是一个多字节编码,属于Unicode编码

//4.打印字符串对象用 %@

 

 

//OC中的字符串是一个字符串对象

//NSString  NSMutableString

//NSString 创建不可变字符串对象

 

 

 

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        NSString *str= @"hello world中国";//常量字符串对象存储在常量区

        NSLog(@"%@", str);

        NSLog(@"%p", str);

        //用给定格式构造一个字符串对象

        NSString *str1 = [[NSString alloc] initWithFormat:@"%s%d%f","hellowrld",1000,3.14];

        NSLog(@"str1 = %@", str1);

        //用另外一个字符串对象构造一个新的字符串对象

        NSString *str2 = [[NSString alloc] initWithString:str1];

        NSLog(@"str2 = %@", str2);

        //用C语言的字符串构造一个OC字符串对象

        NSString *str3 = [[NSString alloc] initWithUTF8String:"qianfeng"];

        NSLog(@"str3 = %@", str3);

        

        NSString *str4 = [[NSString alloc] initWithCString:"1000phone" encoding:NSUTF8StringEncoding];

        NSLog(@"str4 = %@", str4);

        

        //利用类方法创建OC字符串对象

        //构造一个空的字符串对象 @""

        NSString *str5 = [NSString string];

        NSLog(@"str5 = %@", str5);

        //用给定的格式创建一个新的字符串对象

        NSString *str6 = [NSString stringWithFormat:@"%d%s%@",200,"helloworld",@"qianfeng"];

        NSLog(@"str6 = %@", str6);

        //用给定的字符串对象创建一个新的字符串对象

        NSString *str7 = [NSString stringWithString:str6];

        NSLog(@"str7 = %@", str7);

        //用C语言字符串创建OC字符串对象

        NSString *str8 = [NSString stringWithUTF8String:"中国教育"];

        NSLog(@"str8 = %@", str8);

        //用C语言的字符串创建OC字符串对象

        NSString *str9 = [NSString stringWithCString:"千锋教育" encoding:NSUTF8StringEncoding];

        NSLog(@"str9 = %@", str9);

        

    }

    return 0;

}

 

 

#import <Foundation/Foundation.h>

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        NSString *str = [NSString stringWithCString:"helloworld中国教育" encoding:NSUTF8StringEncoding];

        //获取字符串对象长度

        NSUInteger len = [str length];

        NSLog(@"len = %lu %@", len,str);

        //获取下标位置的unichar字符

        unichar ch = [str characterAtIndex:11];

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

        //提取子串

        //从下标位置提取子串到字符串结束

        NSString *str1 = [str substringFromIndex:5];

        NSLog(@"str1 = %@",str1);

        //从字符串开始提取子串到下标位置(不包含下标位置的字符)

        NSString *str2 = [str substringToIndex:5];

        NSLog(@"str2 = %@", str2);

        //提取指定范围内的子串

        NSRange range = {5,6};

        NSString *str3 = [str substringWithRange:range];

        NSLog(@"str3 = %@", str3);

        NSString *str4 = [str substringWithRange:NSMakeRange(5, 5)];//NSMakeRange 创建一个range

        NSLog(@"str4 = %@", str4);

        

        //字符串比较

        NSString *str5 = @"helhelloloworld";

        NSString *str6 = @"hell";

        NSComparisonResult ret = [str5 compare:str6];

        if (ret == NSOrderedAscending) {

            NSLog(@"str5 < str6");

        }

        else if (ret == NSOrderedSame)

        {

            NSLog(@"str5 == str6");

        }

        else if (ret == NSOrderedDescending)

        {

            NSLog(@"str5 > str6");

        }

        //以大小写不敏感方式比较字符串对象

        NSComparisonResult ret2 = [str5 compare:str6 options:NSCaseInsensitiveSearch];

        NSLog(@"ret2 = %ld", ret2);

 

        NSComparisonResult ret3 = [str5 caseInsensitiveCompare:str6];

        NSLog(@"ret3 = %ld", ret3);

        

        //range: 值的调用对象的范围,range.length表示最多比较字符的个数

        NSComparisonResult ret4 = [str5 compare:@"hello" options:NSLiteralSearch range:NSMakeRange(3, 5)];

        NSLog(@"ret10 = %ld", ret4);

 

        //判断两个字符串对象是否相等, 相等返回1,否则返回0

        BOOL ret5 = [str5 isEqualToString:str6];

        NSLog(@"ret4 = %d", ret5);

        //判断前缀

//        - (BOOL)hasPrefix:(NSString *)aString;

        NSString *str7 = @"www.baidu.com";

        BOOL ret6 = [str7 hasPrefix:@"www."];

        NSLog(@"ret5 = %d", ret6);

        

        //判断后缀

//        - (BOOL)hasSuffix:(NSString *)aString;

        NSString *str8 = @"baidu.com";

        BOOL ret7 = [str8 hasSuffix:@"com"];

        NSLog(@"ret6 = %d", ret7);

        

        //判断是否包含子串

        //- (BOOL)containsString:(NSString *)aString;

        BOOL ret8 = [@"helloworld" containsString:@"hello"];

        NSLog(@"ret8 = %d", ret8);

        

        //查找子串

        //查找不到子串返回long类型的最大值 (NSNotFound)

        NSString *str9 = @"qianfengjiaoyu";

        NSRange range1 = [str9 rangeOfString:@"hello"];

        if(range1.location == NSNotFound)

        {

            NSLog(@"%lu 没有找到指定的字符串", NSNotFound);

        }

        else

        {

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

        }

        

        //倒序查找子串

        NSRange range2 = [@"qianhelloworldhellofeng" rangeOfString:@"hello" options:NSBackwardsSearch];

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

        

        //字符串追加

        NSString *str10 = [NSString stringWithFormat:@"%s","qianfeng"];

        

        NSLog(@"%p", str10);

        str10 =[str10 stringByAppendingString:@"helloworld"];//创建一个新的字符串对象

        NSLog(@"%p", str10);

        NSLog(@"str10 = %@", str10);

        //格式化追加字符串

        NSString *str11 = [str10 stringByAppendingFormat:@"%f%s%d",3.14,"qianfeng",1000];

        NSLog(@"str11 = %@", str11);

        

        //把字符串转换成数字

        NSLog(@"%ld",[@"123" integerValue]);

        NSLog(@"%.2f",[@"-3.1456" floatValue]);

        //返回公共前缀子串

        NSString *str12 = [@"www.baidu.com" commonPrefixWithString:@"www.hao123.com" options:NSLiteralSearch];

        NSLog(@"str12 = %@", str12);

        //小写转换大写

        NSString *str13 = [@"hello world qian" uppercaseString];

        NSLog(@"str13 = %@", str13);

        //大写转换小写

        NSString *str14 = [@"HEllo WORld" lowercaseString];

        NSLog(@"str14 = %@", str14);

        //把每个单词的首字母转换成大写

        NSString *str15 = [@"hello qian feng world" capitalizedString];

        NSLog(@"str15 = %@", str15);

        //把OC字符串转换成C语言字符串

        const char *str16 = [@"www.baidu.com" cStringUsingEncoding:NSUTF8StringEncoding];

        NSLog(@"%s",str16);

        //字符串替换

        NSString *str17 = [NSString stringWithUTF8String:"worldqianfengworld1000feng"];

        //用新的字符换替换所有指定的字符串

        str17 = [str17 stringByReplacingOccurrencesOfString:@"world" withString:@"www"];

        NSLog(@"str17 = %@", str17);

        //用新的字符串替换指定范围内的字符串

        NSString *str18 = [str17 stringByReplacingCharactersInRange:NSMakeRange(7, 7) withString:@"sina.cn"];

        NSLog(@"str18 = %@", str18);

        

        //利用网址的内容创建字符串对象

        //- (instancetype)initWithContentsOfURL:(NSURL *)url encoding:(NSStringEncoding)enc error:(NSError **)error;

        //+ (instancetype)stringWithContentsOfURL:(NSURL *)url encoding:(NSStringEncoding)enc error:(NSError **)error;

        NSURL *url = [NSURL URLWithString:@"http://www.baidu.com"];

        NSString *str19 = [[NSString alloc] initWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil];

        NSLog(@"str19 = %@", str19);

 

        //利用文件内容创建字符串对象

        //- (instancetype)initWithContentsOfFile:(NSString *)path encoding:(NSStringEncoding)enc error:(NSError **)error;

        //+ (instancetype)stringWithContentsOfFile:(NSString *)path encoding:(NSStringEncoding)enc error:(NSError **)error;

        NSString *str20 = [NSString stringWithContentsOfFile:@"/Users/zhangxueming/Desktop/file.txt" encoding:NSUTF8StringEncoding error:nil];

        NSLog(@"str20 = %@", str20);

        

    }

    return 0;

}

 

 

//NSMutableString

//可变字符串

//可变字符串对象可以被修改

//继承与不可变字符串

//不可变字符串的方法, 可变字符串都可以使用

 

 

int main(int argc, const char * argv[]) {

    @autoreleasepool {

      //在指定的位置增加字符串

        NSMutableString *mulStr = [NSMutableString stringWithUTF8String:"helloworld"];

        [mulStr insertString:@"qianfeng" atIndex:5];

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

        

        //删除指定范围内的字符

        [mulStr deleteCharactersInRange:NSMakeRange(9, 4)];

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

        //追加字符串

        [mulStr appendString:@"baidu.com"];

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

        //格式化追加字符串

        NSMutableString *mulStr1 = [NSMutableString stringWithCString:"中国人" encoding:NSUTF8StringEncoding];

        [mulStr1 appendFormat:@"%@",@"在大连"];

        NSLog(@"mulStr1 = %@", mulStr1);

        //修改字符串对象

        [mulStr1 setString:@"helloworld"];

        NSLog(@"mulStr1 = %@", mulStr1);

        //构造可变字符串对象并设定容量大小,但是可变容量可以被修改

        //+ (NSMutableString *)stringWithCapacity:(NSUInteger)capacity;

        NSMutableString *mulStr2 = [[NSMutableString alloc]initWithCapacity:20];

        [mulStr2 setString:@"千锋"];

        NSLog(@"mulStr2 = %@", mulStr2);

        //字符串替换

        NSMutableString *mulStr3 = [NSMutableString stringWithCapacity:10];

        [mulStr3 appendString:@"helloOnehelloTwohelloThree"];

        //NSLog(@"%@", mulStr3);

        //替换指定范围内的指定所有字符串

//        [mulStr3  replaceOccurrencesOfString:@"hello" withString:@"welcome" options:NSLiteralSearch range:NSMakeRange(0, 16)];

        [mulStr3 replaceOccurrencesOfString:@"hello" withString:@"welcome" options:NSLiteralSearch range:NSMakeRange(0, [mulStr3 length] )];

        

        NSLog(@"mulStr3 = %@", mulStr3);

        //替换(删除)指定范围内的所有字符

        [mulStr3 replaceCharactersInRange:NSMakeRange(7, 10) withString:@""];

        NSLog(@"mulStr3 = %@", mulStr3);

        

    }

    return 0;

}