OC4_NSString操作

//
//  main.m
//  OC4_NSString操作
//
//  Created by zhangxueming on 15/6/10.
//  Copyright (c) 2015年 zhangxueming. All rights reserved.
//

#import <Foundation/Foundation.h>

//NSString
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSString *str1 = @"hello world 千锋";
        //求字符串长度
        NSUInteger len = [str1 length];
        NSLog(@"len = %li", len);
        //获取字符串指定位置的字符
        unichar ch = [str1 characterAtIndex:13];
        NSLog(@"ch = %C", ch);//%C打印unichar字符 %c打印ASCII字符
        
        //字符串提取
        //从传入下标位置提取子串到字符串结束
        NSString *subStr1 = [str1 substringFromIndex:4];
        NSLog(@"subStr1 = %@", subStr1);
        //提取子串到指定位置(不包含下标位置字符)
        NSString *subStr2 = [str1 substringToIndex:7];
        NSLog(@"subStr2 = %@",subStr2);
        
        //提取指定范围内的字符串
        NSRange range = {6,5};
        NSString *subStr3 = [str1 substringWithRange:range];
        NSLog(@"subStr3 = %@",  subStr3);
        
        //NSMakeRange();//构建NSRange变量
        NSString *subStr4 = [str1 substringWithRange:NSMakeRange(2, 6)];
        NSLog(@"subStr4 = %@", subStr4);
        
        //字符串比较
        NSString *str2 = [NSString stringWithCString:"hallo world中国" encoding:NSUTF8StringEncoding];
        NSString *str3 = [NSString stringWithUTF8String:"hello world中国"];
        NSComparisonResult result = [str2 compare:str3];
        if (result == NSOrderedAscending) {//递增
            NSLog(@"str2 < str3");
        }
        else if(result == NSOrderedDescending)//递减
        {
            NSLog(@"str2 > str3");
        }
        else
        {
            NSLog(@"str2 == str3");
        }
        //以大小写不敏感方式比较字符串
        //[str2 caseInsensitiveCompare:str3];
        //判断两个字符串是否相等
        //- (BOOL)isEqualToString:(NSString *)aString;
        BOOL ret = [str2 isEqualTo:str3];
        if (ret==YES) {
            NSLog(@"str2 == str3");
        }
        else
        {
            NSLog(@"str2 != str3");
        }
        //判断前缀子串
        //- (BOOL)hasPrefix:(NSString *)aString;
        BOOL ret1 = [@"www.baidu.com" hasPrefix:@"www."];
        NSLog(@"ret1 = %d", ret1);
        //判断后缀子串
        //- (BOOL)hasSuffix:(NSString *)aString;
        BOOL ret2 = [@"www.hao123.com" hasSuffix:@"com"];
        NSLog(@"ret2 = %d", ret2);
        //判断是否包含子串(10.10macos)
        BOOL ret3 = [@"hao123" containsString:@"hao"];
        NSLog(@"ret3 = %d", ret3);
        
        //查找子串
        NSString *str4 = [[NSString alloc] initWithFormat:@"%s","hello world qianworldfeng"];
        NSRange range1 =[str4 rangeOfString:@"world"];
        if (range1.location == NSNotFound) {//不能查找对应的子串, 返回long类型最大值
            NSLog(@"没有查找到字串 notfound = %lu", NSNotFound);
        }
        else
        {
            NSLog(@"location = %lu length = %lu", range1.location, range1.length);
        }
        
        //倒序查找子串
        NSRange range2 = [str4 rangeOfString:@"world" options:NSBackwardsSearch];
        NSLog(@"location = %li length = %li", range2.location, range2.length);
        
        //字符串追加
        //并不是直接在原字符串的末尾追加字符串, 而是利用传入的字符串及原字符串创建一个新的字符串
        NSString *str5 = @"hello";
        NSLog(@"%p", str5);
        str5 = [str5 stringByAppendingString:@"world"];
        NSLog(@"str5 = %@", str5);
        NSLog(@"%p", str5);
        
        //格式化追加字符串
        NSString *str6 = @"qianfeng";
        str6 = [str6 stringByAppendingFormat:@"%d%s",123,"helloworld"];
        NSLog(@"str6 = %@", str6);
        
        //把字符换串对象转换成整型 浮点型
        int a = [@"12345" intValue];
        float f = [@"3.14" floatValue];
        NSLog(@"a = %d f = %.2f", a, f);
        
        //返回公共前缀子串
        NSString *str7 = [@"www.baidu.com" commonPrefixWithString:@"www.hao123.com" options:NSLiteralSearch];
        NSLog(@"str7 = %@", str7);
        
        //大小写转换
        //把小写字母转换成大写字母
        NSString *str8 = [@"baidu中国" uppercaseString];
        NSLog(@"str8 = %@", str8);
        //把大写字母转换成小写字母
        NSString *str9 = [@"BaiDU" lowercaseString];
        NSLog(@"str9 = %@", str9);
        //把每个单词的首字母大写
        NSString *str10= [@"bai du qian feng" capitalizedString];
        NSLog(@"str10 = %@", str10);
        
        //字符串替换
        //- (NSString *)stringByReplacingOccurrencesOfString:(NSString *)target withString:(NSString *)replacement
        NSString *str11= @"hello world qianfeng hello world hello hell qianfeng";
        str11 = [str11 stringByReplacingOccurrencesOfString:@"hello" withString:@"welcome"];
        NSLog(@"str11 = %@", str11);
        
        //替换指定范围内的字符
        //- (NSString *)stringByReplacingCharactersInRange:(NSRange)range withString:(NSString *)replacement
        NSString *str12 = @"hello world qianfeng";
        str12 = [str12 stringByReplacingCharactersInRange:NSMakeRange(12, 8) withString:@"welcome"];
        NSLog(@"str12 = %@", str12);
        
        //把OC的字符串对象转换成C字符串
        NSLog(@"%s", [@"hello world" UTF8String]);
        
        //用网址的内容生成OC字符串对像
        //- (instancetype)initWithContentsOfURL:(NSURL *)url encoding:(NSStringEncoding)enc error:(NSError **)error;
        //+ (instancetype)stringWithContentsOfURL:(NSURL *)url encoding:(NSStringEncoding)enc error:(NSError **)error;
        NSURL *url= [[NSURL alloc] initWithString:@"http://www.baidu.com"];
        NSString *urlContent = [[NSString alloc] initWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil];//nil 空指针
        NSLog(@"urlContent = %@", urlContent);
        
        //用文件的内容生成字符串
        //- (instancetype)initWithContentsOfFile:(NSString *)path encoding:(NSStringEncoding)enc error:(NSError **)error;
        //+ (instancetype)stringWithContentsOfFile:(NSString *)path encoding:(NSStringEncoding)enc error:(NSError **)error;
        NSString *fileContent = [NSString stringWithContentsOfFile:@"/Users/zhangxueming/Desktop/json.txt" encoding:NSUTF8StringEncoding error:nil];
        NSLog(@"fileContent = %@", fileContent);
        
    }
    return 0;
}