Object-C中的字符串对象1-不可变字符串

#import <Foundation/Foundation.h>

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

    @autoreleasepool {

        NSString *str1=@"this is string A";
        NSString *str2=@"this is string B";
        NSString *temp;
        NSComparisonResult compareResult;

        //01.计算字符串中字符个数
        NSLog(@"字符串长度：%@的长度为%lu",str1,[str1 length]);

        //02.将一个字符串复制到另一字符串
        temp=[NSString stringWithString:str1];
        NSLog(@"字符串复制：%@",temp);

        //03.将一个字符串复制到另一字符串末尾
        temp=[str1 stringByAppendingString:str2];
        NSLog(@"字符串拼接：%@",temp);

        //04.验证两个字符串是否相等
        if([str1 isEqualToString:str2])
        {
            NSLog(@"字符串比较：%@与%@相同",str1,str2);
        }
        else
        {
            NSLog(@"字符串比较：%@与%@不相同",str1,str2);
        }

        //05.验证一个字符串是否小于，等于或大于另一字符串
        compareResult=[str1 compare:str2];
        if(compareResult==NSOrderedAscending){NSLog(@"字符串比较：%@<%@",str1,str2);}
        else if(compareResult==NSOrderedSame){NSLog(@"字符串比较：%@=%@",str1,str2);}
        else{NSLog(@"字符串比较：%@>%@",str1,str2);}

        //06.将字符串转为大写
        temp=[str1 uppercaseString];
        NSLog(@"字符串大写：%@",temp);

        //07.将字符串转为小写
        temp=[str1 lowercaseString];
        NSLog(@"字符串小写：%@",temp);

        //08.从字符串中取前3个字符
        temp=[str1 substringToIndex:3];
        NSLog(@"字符串截取：%@",temp);

        //09.从字符串中截取第5个字符以后的字符
        temp=[str1 substringFromIndex:5];
        NSLog(@"字符串截取：%@",temp);

        //10.截取从索引5到索引13的子字符
        temp=[[str1 substringFromIndex:5]substringToIndex:8];
        NSLog(@"字符串截取：%@",temp);

        temp=[str1 substringWithRange:NSMakeRange(5, 8)];
        NSLog(@"字符串截取：%@",temp);

        //11.从另一字符串查找一个字符串
        NSString *subStr=@"string A";
        NSRange subRange=[str1 rangeOfString:subStr];
        NSLog(@"字符串查找：%@位于%@第:%lu个字符，长度为:%lu",subStr,str1,subRange. location,subRange .length);

        subRange=[str2 rangeOfString:subStr];
        if(subRange.location==NSNotFound)
        {
            NSLog(@"字符串查找：%@中不存在%@",str2,subStr);
        }
        else
        {
            NSLog(@"字符串查找：%@中存在%@",str2,subStr);
        }

    }
    return 0;
}

输出结果：

2014-02-12 22:41:43.890 05.字符串[1560:303]字符串长度：this is string A的长度为16

2014-02-12 22:41:43.892 05.字符串[1560:303]字符串复制：this is string A

2014-02-12 22:41:43.892 05.字符串[1560:303]字符串拼接：this is string Athis is string B

2014-02-12 22:41:43.892 05.字符串[1560:303]字符串比较：this is string A与this
is string B不相同

2014-02-12 22:41:43.893 05.字符串[1560:303]字符串比较：this is string A<this is string B

2014-02-12 22:41:43.893 05.字符串[1560:303]字符串大写：THIS IS STRING A

2014-02-12 22:41:43.893 05.字符串[1560:303]字符串小写：this is string a

2014-02-12 22:41:43.893 05.字符串[1560:303]字符串截取：thi

2014-02-12 22:41:43.894 05.字符串[1560:303]字符串截取：is string A

2014-02-12 22:41:43.894 05.字符串[1560:303]字符串截取：is strin

2014-02-12 22:41:43.894 05.字符串[1560:303]字符串截取：is strin

2014-02-12 22:41:43.895 05.字符串[1560:303]字符串查找：string A位于this
is string A第:8个字符，长度为:8

2014-02-12 22:41:43.895 05.字符串[1560:303]字符串查找：this is string B中不存在string
A

Program ended with exit code: 0