创建字符串，字符串的获取

#import <Foundation/Foundation.h>

//1 创建字符串的方式
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
     
        NSString * str = @"oc str";
        NSLog(@"str %@",str);
     
        char * c = "c str";
        char * c1 = "我是c语言字符串";
        NSString * str1 = [[NSString alloc] initWithCString:c1  encoding:NSUTF8StringEncoding];
        NSLog(@"str1 %@",str1);
       
        int i = 10;
        NSString * str2 = [[NSString alloc] initWithFormat:@"format %@ %d",str1,i];
        NSLog(@"str2 %@",str2);
        int year = 2016;
        int month = 09;
        int day = 20;
        
       
        NSString * str3 = [[NSString alloc] initWithFormat:@"%d年%02d月%d日",year,month,day];
        NSLog(@"%@",str3);
    }
    return 0;
}

/*
1> 获取字符串的长度
2 >根据索引获得单个字符
3 >根据索引获得一个子串
4 >根据字符串获得该字符串在另一个字符串中的索引位置
 */
#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
       
      NSString * str = @"baidu";
        NSUInteger count = [str length];
        NSLog(@"%lu",count);
      
        char c = [str characterAtIndex:0];
        NSLog(@"%d",c);
        
     
        NSString * substr1 = [str substringFromIndex:3];
        NSLog(@"substr1 %@",substr1);
       
        NSString * substr2 = [str substringToIndex:3];
        NSLog(@"substr2 %@",substr2);
        NSRange range = {2,3};
        /*
        NSUInteger location 起始位置
        NSUInteger length 长度
         */
        // substringWithRange 从loccation开始的length个字符
        NSString * substr3 = [str substringWithRange:range];
        NSLog(@"%@",substr3);
       
        NSString * str1 = @"www.baidu.com";
        NSRange range2 = [str1 rangeOfString:str];
      
        NSLog(@"%@",NSStringFromRange(range2));
    }
    return 0;
}