字符串的赋值和字符串数组

字符串在任何语言中是很重要，所以我们应该熟练的掌握

//
//  main.m
//  stringTest
//
//  Created by wen jing on 12-8-4.
//  Copyright (c) 2012年 __MyCompanyName__. All rights reserved.
//

#import 

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

    @autoreleasepool {
        
        // insert code here...
        NSLog(@"Hello, World!");
        ////////////关于字符串的赋值//////////////
        //1）赋值方法常量
        NSString *str = @"This is a String!";
        /*
         Log:
            2012-08-04 22:32:58.687 stringTest[441:903] Hello, World!
         
         */
        //输出字符串 %@
        NSLog(@"str value==%@",str);
        /*
         log:
         2012-08-04 22:32:58.701 stringTest[441:903] str value==This is a String!
         
         */
        
        //2）赋值方法
        NSString *str2 = [[NSString alloc] init];
        
        str2 = @"this is a String 2";
        
        
        NSLog(@"str2 value=%@",str2);
        [str2 release];//释放内存
        /*
         Log:
         2012-08-04 22:37:30.295 stringTest[496:903] str1 value=this is a String 2

         */
         
        //3赋值方法（效率高）
        
        NSString *str3=[[NSString alloc] initWithString:@"this is a string 3"];
        NSLog(@"str3 value=%@",str3);
         [str3 release];
        /*
         Log:
         2012-08-04 22:48:33.439 stringTest[568:903] str3 value=this is a string 3         
         
         */
        //4)赋值方法
        NSString *str4=[[NSString alloc] initWithCString:"this is a string 4"];
        
        NSLog(@"str4 value=%@",str4);
        [str4 release];
        /*
         Log:
         2012-08-04 22:54:49.784 stringTest[646:903] str4 value=this is a string 4
         
         */
        //5)赋值方法
        int i = 1;
        int j = 2;
        NSString *str5 = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];
        NSLog(@"str5 value=%@",str5);
        [str5 release];
        /*
         log:
         2012-08-04 23:06:17.362 stringTest[696:903] str5 value=1.This is 2 string!
         
         */
         
        //6、创建临时字符串
        NSString *str6;
        str6 = [NSString stringWithCString:"This is a temporary string"];
        NSLog(@"astring:%@",str6);
        /*
         log:
         2012-08-04 23:08:04.335 stringTest[716:903] astring:This is a temporary string
         
         */
//        

//数字＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
       
         
        NSString *str7 =[[NSString alloc] initWithString:@"fdsajkkfsdakfa@dskjkafsdk"];
        NSArray *array = [str7 componentsSeparatedByString:@"@"];//就是以@为标示 输出看看啦
        
        int count=[array count];
       
        for(int j=0;j