#import <Foundation/Foundation.h>
int main(int argc,const char * argv[])
{
    @autoreleasepool {
        NSNumber *myNumber,*floatNumber,*intNumber;
       
        intNumber=[NSNumber numberWithInt:100];
        NSLog(@"%li",[intNumber integerValue]);//100
       
        floatNumber=[NSNumber numberWithFloat:100.00];
        NSLog(@"%f",[floatNumber floatValue]);//100.000000
       
        myNumber=[NSNumber numberWithChar:'A'];
        NSLog(@"%c",[myNumber charValue]);//A
       
        //判断两个数字是否相等
        if([intNumber isEqualToNumber:floatNumber]==YES)
        {
            NSLog(@"int number is equal to float number");//√
        }
        else{
            NSLog(@"int number is not equal to float number");
        }
       
        //比较两个数字大小
        if([intNumber compare:myNumber]==NSOrderedAscending)
        {
            NSLog(@"int number is less than mynumber");
        }
        else{
            NSLog(@"int number is more than mynumber");//√
        }
         
        //@语法
        intNumber=@200;
        NSLog(@"%li",[intNumber integerValue]);//200
    }
    return 0;
}

#import <Foundation/Foundation.h>
@interface Complex : NSObject
@property int real,imaginary;
-(void)setReal:(int)r andImaginary:(int)m;
@end

#import "Complex.h"
@implementation Complex
@synthesize real,imaginary;
-(void)setReal:(int)r andImaginary:(int)m
{
    self.real=r;
    self.imaginary=m;
}
//重写description,自定义输出格式
-(NSString *)description
{
    return [NSString stringWithFormat:@"%i + %ii",self.real,self.imaginary];
}
@end

#import <Foundation/Foundation.h>
#import "Complex15.h"
int main(int argc,const char * argv[])
{
    @autoreleasepool {
        Complex15 *c=[[Complex15 alloc] init];
        [c setReal:1 andImaginary:2];
        NSLog(@"%@",c);//由<Complex15: 0x10010ffa0> 变为 1 + 2i
    }
    return 0;
}

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

    @autoreleasepool {
        NSString *str1=@"This is String A";
        NSString *str2=@"This is String B";
        NSString *result;
        NSComparisonResult compareResult;

        // 字符串长度
        NSLog(@"length of str1 is %lu",[str1 length]);//length of str1 is 16
        //复制字符串
        result=[NSString stringWithString:str1];
        NSLog(@"Copy str1,result is: %@",result);//Copy str1,result is: This is String A
        //追加字符串
        str2=[str1 stringByAppendingString:str2];
        NSLog(@"str1 append str2 is:%@",str2);//str1 append str2 is:This is String AThis is String B
        //字符串是否相等
        if([str1 isEqualToString:result]){
            NSLog(@"str1==result");//√
        }
        else{
            NSLog(@"str!=str2");
        }
        //比较字符串
        compareResult=[str1 compare:str2];
        if(compareResult==NSOrderedAscending){
            NSLog(@"str1<str2");//√
        }else if(compareResult==NSOrderedSame){
            NSLog(@"str1=str2");
        }else{
            NSLog(@"str1>str2");
        }
        //大小写转换
        result=[str1 uppercaseString];
        NSLog(@"upper case:%@",result);//upper case:THIS IS STRING A
        result=[str1 lowercaseString];
        NSLog(@"lower case:%@",result);//lower case:this is string a
    }
    return 0;
}
 

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

    @autoreleasepool {
        NSString *str1=@"This is String A";
        NSString *result;
        NSRange range;
       
        //从开头取前N个字符
        result=[str1 substringToIndex:4];
        NSLog(@"前4个字符:%@",result);//前4个字符:This
        //取第N个字符到结尾
        result=[str1 substringFromIndex:8];
        NSLog(@"后8个字符:%@",result);//后8个字符:String A
        //提取第8到13个字符
        result=[[str1 substringFromIndex:8] substringToIndex:6];
        NSLog(@"第8到13个字符：%@",result);//第8到13个字符：String
        //另一种实现方式
        result=[str1 substringWithRange:NSMakeRange(8,6)];
        NSLog(@"第8到13个字符：%@",result);//第8到13个字符：String
        //查找子串
        range=[str1 rangeOfString:@"String"];
        NSLog(@"String子串位置%lu,长度是%lu",range.location,range.length);//String子串位置8,长度是6
        //查找不存在的子串
        range=[str1 rangeOfString:@"StringA"];
        if(range.location==NSNotFound){
            NSLog(@"未找到子串StringA");//√
        }else{
            NSLog(@"子串StringA位置为%lu",range.location);
        }
     }
}

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

    @autoreleasepool {
        NSString *str=@"This is String A";
        NSMutableString *mstr;
        NSRange substr;
       
        mstr=[NSMutableString stringWithString:str];
        NSLog(@"%@",mstr);//This is String A
        //插入字符
        [mstr insertString:@" mutable" atIndex:7];
        NSLog(@"%@",mstr);//This is mutable String A
        //追加字符
        [mstr appendString:@" and String B"];
        NSLog(@"%@",mstr);//This is mutable String A and String B
        //删除子串
        [mstr deleteCharactersInRange:NSMakeRange(16, 8)];
        NSLog(@"%@",mstr);//This is mutable  and String B
        //查找子串并删除
        substr=[mstr rangeOfString:@"and String B"];
        if(substr.location!=NSNotFound){
            [mstr deleteCharactersInRange:substr];
            NSLog(@"%@",mstr);//This is mutable
        }
        //直接设置可变字符串内容
        [mstr setString:@"This is String."];
        NSLog(@"%@",mstr);//This is String.
        //替换子串
        [mstr replaceCharactersInRange:NSMakeRange(7, 1) withString:@" mutable "];
        NSLog(@"%@",mstr);//This is mutable String.