objective c 字符串各种处理（转）

原地址：http://blog.csdn.net/dingkun520wy/article/details/7010270

关于字符串的各种操作，总结一下以便以后复习查找。

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;