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objective-c 字符串各种处理

内容简要:

1、创建常量字符串。

2、创建空字符串,给予赋值。

3、在以上方法中,提升速度:initWithString方法

4、用标准c创建字符串:initWithCString方法。

5、创建格式化字符串:占位符(由一个%加一个字符组成)

6、创建临时字符串。

7、判断字符串为空。

9、是否以”test”开头;是否以”.move”结尾。

10、比较两个字符串。

11、声明一个可变字符;长度是40个字符。

12、修改可变字符;先声明一个可变字符 myFriend;长度30。

13、在一个字符串后面附加一个新的字符串。

14、字符串转换整数值。

15、从文件读取字符串:initWithContentsOfFile方法。

16、写字符串到文件:writeToFile方法

17、改变字符串的大小写。

18、在串中搜索子串。

19、抽取子串。

20、扩展路径。

21、文件扩展名。

22、在已有字符串后面添加字符。

23、在已有字符串中按照所给出范围和长度删除字符。

24、在已有字符串后面在所指定的位置中插入给出的字符串。

25、将已有的空符串换成其它的字符串。

26、按照所给出的范围,和字符串替换的原有的字符。

27、判断字符串内是否还包含别的字符串(前缀,后缀)。

 

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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); 

 

7、判断字符串为空

NSString *urlString = [urlInput stringValue];
if (!urlString) { 
NSLog( @”NO INPUT.” );
}
if ([urlString length] == 0 ) {
NSLog( @”NO INPUT.” );

 

 

 

9、是否以”test”开头;是否以”.move”结尾;

NSString *fileName = @”test.move”;

if ([fileName hasPrefix:@"test"]) {

NSLog(@”has Test String !”);

}else{

NSLog(@”don’t have Test”);

}

 

[fileName hasSuffix:@".move"]?NSLog(@”Yes it got a .Mov in its end”):NSLog(@”no it has no .mov string”);

 

 

 

10、比较两个字符串:

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)

 

不考虑大小写比较字符串2
   NSString *astring01 = @"this is a String!";
   NSString *astring02 = @"This is a String!";
   BOOL result = [astring01 compare:astring02
                           options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;    
   NSLog(@"result:%d",result);     

NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较,区分大小写NSNumericSearch:比较字符串的字符个数,而不是字符值。

 

11、声明一个可变字符;长度是40个字符;

NSMutableString *myMutableString;

myMutableString = [NSMutableString stringWithCapacity:40];

NSString *myName = @”Leo”;

[myMutableString appendString:@"Hello ,there"];

[myMutableString appendFormat:@" i am %@",myName];

NSLog(@”this is NSMutableString: %@”,myMutableString);

//this is NSMutableString: Hello ,there i am Leo;

12、修改可变字符;先声明一个可变字符 myFriend;长度30;

 

NSMutableString *myGirlFriend;

myGirlFriend = [NSMutableString stringWithCapacity:30];

//然后给字符加入一些内容;

[myGirlFriend appendString:@"Here are my GF:Carol Sophia Ashley Helen and Yoyo"];

NSLog(@”%@”,myGirlFriend);

//声名一个变动范围(NSRange);

NSRange joneRange;

joneRange = [myGirlFriend rangeOfString:@"Helen "];

//下面:就是从myFriend字符中配对,如果有相等的内容就删除了;

[myGirlFriend deleteCharactersInRange:joneRange];

NSLog(@”%@”,myGirlFriend);

13、在一个字符串后面附加一个新的字符串

NSString *a = @"a";

NSString *b = [a stringByAppendingString:@"b"];//b变量的值为“ab”

14、字符串转换整数值

NSString *age = @"36";

if([age intValue]>35){

}

15、从文件读取字符串:initWithContentsOfFile方法
   NSString *path = @"astring.text";
   NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
   NSLog(@"astring:%@",astring);
   [astring release];

16、写字符串到文件:writeToFile方法
   NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
   NSLog(@"astring:%@",astring);
   NSString *path = @"astring.text";    
   [astring writeToFile: path atomically: YES];
   [astring release];   

 

17、改变字符串的大小写

   NSString *string1 = @"A String"; 
   NSString *string2 = @"String"; 
   NSLog(@"string1:%@",[string1 uppercaseString]);//大写
   NSLog(@"string2:%@",[string2 lowercaseString]);//小写
   NSLog(@"string2:%@",[string2 capitalizedString]);//首字母大小

 

18、在串中搜索子串

   NSString *string1 = @"This is a string";
   NSString *string2 = @"string";
   NSRange range = [string1 rangeOfString:string2];
   int location = range.location;
   int leight = range.length;
   NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
   NSLog(@"astring:%@",astring);
   [astring release];

 

19、抽取子串

   //-substringToIndex: 从字符串的开头一直截取到指定的位置,但不包括该位置的字符
   NSString *string1 = @"This is a string";
   NSString *string2 = [string1 substringToIndex:3];
   NSLog(@"string2:%@",string2);
   //-substringFromIndex: 以指定位置开始(包括指定位置的字符),并包括之后的全部字符
   NSString *string1 = @"This is a string";
   NSString *string2 = [string1 substringFromIndex:3];
   NSLog(@"string2:%@",string2);


   //-substringWithRange: //按照所给出的位置,长度,任意地从字符串中截取子串
   NSString *string1 = @"This is a string";
   NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
   NSLog(@"string2:%@",string2);


20、扩展路径

   NSString *Path = @"~/NSData.txt";
   NSString *absolutePath = [Path stringByExpandingTildeInPath];
   NSLog(@"absolutePath:%@",absolutePath);
   NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);



21、文件扩展名
   NSString *Path = @"~/NSData.txt";
   NSLog(@"Extension:%@",[Path pathExtension]);


22、在已有字符串后面添加字符  
   NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
   //[String1 appendString:@", I will be adding some character"];
   [String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
   NSLog(@"String1:%@",String1);

23、在已有字符串中按照所给出范围和长度删除字符

    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 deleteCharactersInRange:NSMakeRange(0, 5)];
    NSLog(@"String1:%@",String1);



24、在已有字符串后面在所指定的位置中插入给出的字符串

   //-insertString: atIndex:
   NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
   [String1 insertString:@"Hi! " atIndex:0];
   NSLog(@"String1:%@",String1);

25、将已有的空符串换成其它的字符串

   //-setString:
   NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
   [String1 setString:@"Hello Word!"];
   NSLog(@"String1:%@",String1);

26、按照所给出的范围,和字符串替换的原有的字符

   //-setString:
   NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
   [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
   NSLog(@"String1:%@",String1);

27、判断字符串内是否还包含别的字符串(前缀,后缀)
   //01:检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString *) aString;
   NSString *String1 = @"NSStringInformation.txt";
   [String1 hasPrefix:@"NSString"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");
   [String1 hasSuffix:@".txt"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");
   //02:查找字符串某处是否包含其它字符串 - (NSRange) rangeOfString: (NSString *) aString,这一点前面在串中搜索子串用到过;


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