Objective-C 对字符串的操作

//
//  main.m
//  OCdemo-04-00
//
//  Created by lanou3g on 15/10/12.
//  Copyright (c) 2015年 Object. All rights reserved.
//

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
       /*
//             NSString  不可改变的字符串
//             对象创建完成以后，内容和长度不能更改
        
        // 1.创建字符串
        //使用初始化方法
        NSString *string1 = [[NSString alloc] initWithFormat:@"hello kity1"];
        //使用类方法
        NSString *string2 = [NSString stringWithFormat:@"hello kity2"];
        //使用字面量方法
        NSString *string3 = @"hello kity3";
        
        //2.获取字符串长度
        NSUInteger str1length = [string1 length];
        NSLog(@"length = %lu",str1length);
        
        //3.获取指定位置的字符(注意不能越界)
        NSUInteger str2length = [string2 length];
        
        char c1 = [string2 characterAtIndex:10];
        char c2 = [string2 characterAtIndex:str2length - 1];
        NSLog(@"%c",c1);
        NSLog(@"%c",c2);

        //4.判断字符串的前缀、后缀
        BOOL isHasPrefix = [string3 hasPrefix:@"hello"];
        NSLog(@"%d",isHasPrefix);
        
        NSString *string4 = @"dahuang.png";
        BOOL isHasSuffix = [string4 hasSuffix:@".png"];
        NSLog(@"%d",isHasSuffix);
        
        //5.查找某个字符串在另一个字符串的范围
        //  location : 开始位置
        //  length : 长度
        
        NSString *string5 = @"北京蓝鸥科技有限公司";
        NSString *string6 = @"蓝鸥科技";
        NSRange range1 = [string5 rangeOfString:string6];
        NSLog(@"location = %lu,length = %lu",range1.location,range1.length);
        
        //6.字符串截取
        //(1)通过位置和长度截取字符串
        NSRange range2 = NSMakeRange(6, 4);
        NSString *subStr5 = [string5 substringWithRange:range2];
        NSLog(@"sunStr5 = %@",subStr5);
        
        //(2)指定位置向后截取字符串
        NSString *str2Str5 = [string5 substringFromIndex:2];
        NSLog(@"%@",str2Str5);
        //(3)指定位置向前截取
        NSString *str3Str5 = [string5 substringToIndex:6];
        NSLog(@"%@",str3Str5);
        
        
        //7.字符串拼接
        NSString *string7 = @"北京蓝鸥科技";
        NSString *string8 = @"有限公司";
        
        string7 = [string7 stringByAppendingString:string8];
        NSLog(@"%@",string7);
        
        //8.字符串替换
        NSString *string9 = @"黄星杰";
        string9 = [string9 stringByReplacingOccurrencesOfString:string9 withString:@"大黄"];
        NSLog(@"string9 = %@",string9);
        
        //9.字符串比较
        NSString *string10 = @"huangxingjie";
        NSString *string11 = @"liugaojian";
        NSInteger result = [string10 compare:string11];
        NSLog(@"%ld",result);
        
        //判断某个字符串是否和另一个字符串相等
        NSLog(@"%d",[string10 isEqualToString:@"huangxingjie"]);
        
        //10.字符串和数值的类型转换
        NSString *string12 = @"123";
        NSInteger value1 = [string12 integerValue];
        NSLog(@"%ld",value1);
        
        //11.字符串大小写转换
        NSString *string13 = @"ALu";
        //把字符串转成小写
        NSLog(@"%@",[string13 lowercaseString]);
        //把字符串转成大写
        NSLog(@"%@",[string13 uppercaseString]);
        //字符串首字母大写
        NSString *strName = @"lirui";
        NSLog(@"%@",[strName capitalizedString]);
        //-----------------------------------------
        */
        
        // NSMutableString  可变的字符串
        //  是NSString 的子类，该类创建的字符串是一个动态可变的
        
        //1.创建字符串
        NSMutableString *mstr1 = [NSMutableString stringWithFormat:@"xujin"];
        //2.拼接字符串
        [mstr1 appendString:@"周一见"];
        NSLog(@"%@",mstr1);//xujin周一见
        
        //3.插入字符
        [mstr1 insertString:@"," atIndex:5];
        NSLog(@"%@",mstr1); //xujin,周一见
        
        //4.删除字符串
        NSRange mrange1 = NSMakeRange(0, 6);
        [mstr1 deleteCharactersInRange:mrange1];
        NSLog(@"%@",mstr1); //周一见

        //不可变的字符串的修改方法有返回值（重新指向新的字符串地址）
        //可变的字符串的修改方法没有返回值，修改原字符串
        //----------------------------------------------------------------------
        
        //练习：给定一个图片文件名，判断字符串中是否以“png”结尾，如果是就替换成“jpg”，如果不是，就拼接”.jpg”
        NSString *pic = @"tupian.png";
    
        BOOL isHasSuffix = [pic hasSuffix:@".png"];
        //NSLog(@"%d",isHasSuffix);
        
        if (isHasSuffix == 0) {
            pic = [pic stringByAppendingString:@".jpg"];
        }else{       
            pic = [pic stringByReplacingCharactersInRange:NSMakeRange([pic length] - 3, 3) withString:@"jpg"];
        }
        NSLog(@"%@",pic);
        

        
        
        
    }
    return 0;
}