NSString基础1-创建、长度、比较、判断大小、转换

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
@autoreleasepool {
//创建字符串常量
NSString *str1=@"char1";
//实例方法创建
NSString *str2=[[NSString alloc]init];
NSString *str4=[[NSString alloc]initWithFormat:@"char4"];
NSString *str5=[[NSString alloc]initWithString:str1];
//类方法创建
NSString *str6=[NSString string];
NSString *str7=[NSString stringWithString:str1];
NSString *str8=[NSString stringWithFormat:@"char8"];
//格式化创建
int num1=3;
float num2=4.5;
NSString *str9=[[NSString alloc]initWithFormat:@"%f",num2];
NSString *str10=[[NSString alloc]initWithFormat:@"%d,%f",num1,num2];
NSString *str11=[NSString stringWithFormat:@"%d,%f",num1,num2];

//字符串长度
NSUInteger len=[str1 length];

//字符串比较
if([str7 isEqualToString:str8]){
NSLog(@"They are sam");
}
else{
NSLog(@"They are different");
}

//判断字符串大小
NSComparisonResult result1=[str7 compare:str8];
NSComparisonResult result2=[str7 caseInsensitiveCompare:str8];

//字符串转换
float num3=[str9 floatValue];

//大小写转换
NSString *str12=[[NSString alloc]initWithFormat:@"HelloWorld!"];
NSString *str13=[str12 uppercaseString];
NSString *str14=[str12 lowercaseString];
NSString *str15=[str12 capitalizedString];

//将NSString转换为C语言字符串
const char * str16=[str12 UTF8String];
}
return 0;
}