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iPhone objective-c字符串类NSString的使用

开发过程中,我们会遇到很多关于字符串的操作,它是一个常用的数据类型,下面对它的用法进行了汇总:

  

    //1、创建常量字符串。
    NSString *astring = @"This is a String!";


    //2、创建空字符串,给予赋值。

    NSString *astring = [[NSString alloc] init];
    astring = @"This is a String!";
    NSLog(@"astring:%@",astring);
  [astring release];

//3、在以上方法中,提升速度:initWithString方法

    NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
    NSLog(@"astring:%@",astring);
    [astring release];

 //4、用标准c创建字符串:initWithCString方法

    char *Cstring = "This is a String!";
    NSString *astring = [[NSString alloc] initWithCString:Cstring];
    NSLog(@"astring:%@",astring);
    [astring release];

 

    //5、创建格式化字符串:占位符(由一个%加一个字符组成)

    int i = 1;
    int j = 2;
    NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];
    NSLog(@"astring:%@",astring);
    [astring release];

 

    //6、创建临时字符串

    NSString *astring;
    astring = [NSString stringWithCString:"This is a temporary string"];
    NSLog(@"astring:%@",astring);


    NSString *path = @"astring.text";
    NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
    NSLog(@"astring:%@",astring);
    [astring release];


    NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
    NSLog(@"astring:%@",astring);
    NSString *path = @"astring.text";   
    [astring writeToFile: path atomically: YES];
    [astring release];   
          

    //用C比较:strcmp函数

    char string1[] = "string!";
    char string2[] = "string!";
    if(strcmp(string1, string2) = = 0)
    {
        NSLog(@"1");
    }

   //isEqualToString方法   
    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 isEqualToString:astring02];
    NSLog(@"result:%d",result);

   //compare方法(comparer返回的三种值)   
    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"This is a String!";   
    BOOL result = [astring01 compare:astring02] = = NSOrderedSame;   
    NSLog(@"result:%d",result);   
    //NSOrderedSame 判断两者内容是否相同

    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"this is a String!";
    BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;   
    NSLog(@"result:%d",result);
    //NSOrderedAscending 判断两对象值的大小(按字母顺序进行比较,astring02大于astring01为真)

    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;   
    NSLog(@"result:%d",result);    
    //NSOrderedDescending 判断两对象值的大小(按字母顺序进行比较,astring02小于astring01为真)

//不考虑大 小写比较字符串1
    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;   
    NSLog(@"result:%d",result);    
    //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较,astring02小于astring01为真)

//如何判断字符串为空

NSString *urlString = [urlInput stringValue];

 
if (!urlString) {
 
 
NSLog( @”NO INPUT.” );

 
} else {
 
if ([urlString length] == 0 ) {

 
NSLog( @”NO INPUT.” );

 
} else {

 
}

 
}

补充:移动开发 , Android ,
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