Object-C学习笔记2——字符串操作

字符串的操作

　(1)创建字符串常量

　NSString *str1=@"NSString1";　

　(2)用一个存在的字符串创建一个新的字符串对象　

　NSString *str2=@[NSString stringWithStringLstr1];

　NSString *str22=[[NSString alloc] initWithString:str1];

　(3)按照一定的格式拼接字符串

　int age=20;int score=98;

　NSString *str3=[NSString stringWithFormat:@"xiaoming'sage is %d score is %d",age,score];

　(4)获取字符串长度

　int l=[str3 length];/int l=str3.length;

　(5)比较两个字符串是否相同　　

BOOL result=[str2 isEqualToString:str22];
if(result==YES){
    NSLog(@"the same");
} else {
    NSLog(@"not the same");
}    
NSComparisonResult cmpResult=[@"abd" compare:@"abc"];
if(cmpResult==NSOrderedAscending){
    NSLog(@"ascending");
} else if(cmpResult==NSOrderedSame){
    NSLog(@"the same");
} else {
    NSLog(@"not the same");
}

　(6)获取字符串前缀后缀

NSString *httpStr=@"http://www.baidu.com"; 
if([httpStr hasPrefix:@"http"]){
    NSLog(@"YES");
} else {
    NSLog(@"NO");
}
if([httpStr hasSuffix:@".com"]){
    NSLog(@"YES");
} else {
    NSLog(@"NO");
}

   (7)截取字符串

NSString *sTemp1=@"hello world";
NSLog(@"%@",[sTemp1 substringFromIndex:3]); //去掉开头长度为3的字符串
NSLog(@"%@",[sTemp1 substringToIndex:3]); //取开头长度为3的字符串
NSRange range = NSMakeRange(3,4);        
NSLog(@"%@",[sTemp1 substringWithRange:range]);    //从第三个字符开始截取长度为4的字符串
NSRange sRange=[sTemp1 rangeOfString:@"worl"];    //查询字符串sTemp1中是否包含“worl”
if(sRange.length !=0){
    NSLog(@"exist location:%lu",sRange.location);
} else {
    NSLog(@"not exist");
}

　(8)字符串数字转换为对应的数据类型

NSString *numStr=@"123.12";
int num=[numStr intValue];          //转换为int类型
double dou=[numStr doubleValue];  //转换为double类型

   (9)字符串转换为数组

NSString *arrayStr=@"abc,bcd,cde,def";
NSArray *array=[arrayStr componentsSeparatedByString:@","];  

　(10)可变字符的操作

//创建可变字符串
NSMutableString *orgStr=[NSMutableString stringWithString:@"GuiZhou University of Finance and Economics"];
//字符串替换
[orgStr replaceCharactersInRange:NSMakeRange(8,7) withString:@"guida"];
NSLog(@"%@",orgStr);
//插入字符
[orgStr insertString:@" big" atIndex:7];
NSLog(@"%@",orgStr);
//追加字符串
[orgStr appendString:@" OKK"];
NSLog(@"%@",orgStr);
//重新设置字符串
[orgStr setString:@"xiaohuang"];
NSLog(@"%@",orgStr);
//查找全部匹配字符并替换
NSRange orgStr1=[orgStr rangeOfString:@"a"];
while(orgStr1.location!=NSNotFound){
                [orgStr replaceCharactersInRange:orgStr1 withStrig:@"P"];
    orgStr=[orgStr rangeOfString:@"a"];
}
NSLog(@"%@",orgStr);
//删除一些字符
[orgStr deleteCharactersInRange:NSMakeRange(0,4)];
NSLog(@"%@",orgStr);