objective c 字符串各類處理

關於字符串的各類操做，總結一下以便之後複習查找。

內容簡要:

1、建立常量字符串。 2、建立空字符串，給予賦值。3、在以上方法中，提高速度:initWithString方法

 

4、用標準c建立字符串:initWithCString方法。5、建立格式化字符串:佔位符（由一個%加一個字符組成）

 

6、建立臨時字符串。七、判斷字符串爲空。9、是否以」test」開頭;是否以」.move」結尾。十、比較兩個字符串。

 

十一、聲明一個可變字符;長度是40個字符。十二、修改可變字符;先聲明一個可變字符 myFriend;長度30。

 

13、在一個字符串後面附加一個新的字符串。14、字符串轉換整數值。

 

1五、從文件讀取字符串:initWithContentsOfFile方法。16、寫字符串到文件:writeToFile方法

 

17、改變字符串的大小寫。1八、在串中搜索子串。19、抽取子串。20、擴展路徑。21、文件擴展名。

 

22、在已有字符串後面添加字符。23、在已有字符串中按照所給出範圍和長度刪除字符。

 

2四、在已有字符串後面在所指定的位置中插入給出的字符串。25、將已有的空符串換成其它的字符串。

 

2六、按照所給出的範圍，和字符串替換的原有的字符。2七、判斷字符串內是否還包含別的字符串(前綴，後綴)。

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

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1、建立常量字符串。
 NSString *astring = @"This is a String!";

 2、建立空字符串，給予賦值。

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

3、在以上方法中，提高速度:initWithString方法

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

4、用標準c建立字符串:initWithCString方法

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

5、建立格式化字符串:佔位符（由一個%加一個字符組成）

    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、建立臨時字符串

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

七、判斷字符串爲空

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

9、是否以」test」開頭;是否以」.move」結尾;

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」);

十、比較兩個字符串:

strcmp函數

    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返回的三種值)    
    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"This is a String!";    
    BOOL result = [astring01 compare:astring02] = = NSOrderedSame;    
    NSLog(@"result:%d",result);    
    NSOrderedSame 判斷二者內容是否相同

    

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

    NSOrderedAscending 判斷兩對象值的大小(按字母順序進行比較，astring02大於astring01爲真)

    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;    
    NSLog(@"result:%d",result);     
    NSOrderedDescending 判斷兩對象值的大小(按字母順序進行比較，astring02小於astring01爲真)

不考慮大 小寫比較字符串1
    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;    
    NSLog(@"result:%d",result);

NSOrderedDescending判斷兩對象值的大小(按字母順序進行比較，astring02小於astring01爲真)

不考慮大小寫比較字符串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:不區分大小寫比較 NSLiteralSearch:進行徹底比較，區分大小寫NSNumericSearch:比較字符串的字符個數，而不是字符值。

十一、聲明一個可變字符;長度是40個字符;

　　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;

　　

十二、修改可變字符;先聲明一個可變字符 myFriend;長度30;

　　NSMutableString *myGirlFriend;

　　myGirlFriend = [NSMutableString stringWithCapacity:30];

　　//而後給字符加入一些內容;

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

　　NSLog(@」%@」,myGirlFriend);

　　//聲名一個變更範圍(NSRange);

　　NSRange joneRange;

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

　　//下面:就是從myFriend字符中配對,若是有相等的內容就刪除了;

　　[myGirlFriend deleteCharactersInRange:joneRange];

　　NSLog(@」%@」,myGirlFriend);

13、在一個字符串後面附加一個新的字符串

NSString *a = @"a";

NSString *b = [a stringByAppendingString:@"b"];//b變量的值爲「ab」

14、字符串轉換整數值

NSString *age = @"36";

if([age intValue]>35){

}

1五、從文件讀取字符串:initWithContentsOfFile方法
    NSString *path = @"astring.text";
    NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
    NSLog(@"astring:%@",astring);
    [astring release];

16、寫字符串到文件: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、改變字符串的大小寫

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

1八、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: 從字符串的開頭一直截取到指定的位置，但不包括該位置的字符
    NSString *string1 = @"This is a string";
    NSString *string2 = [string1 substringToIndex:3];
    NSLog(@"string2:%@",string2);

    //-substringFromIndex: 以指定位置開始（包括指定位置的字符），幷包括以後的所有字符
    NSString *string1 = @"This is a string";
    NSString *string2 = [string1 substringFromIndex:3];
    NSLog(@"string2:%@",string2);
 
 
    //-substringWithRange: //按照所給出的位置，長度，任意地從字符串中截取子串
    NSString *string1 = @"This is a string";
    NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
    NSLog(@"string2:%@",string2);
 
 
20、擴展路徑
 
    NSString *Path = @"~/NSData.txt";
    NSString *absolutePath = [Path stringByExpandingTildeInPath];
    NSLog(@"absolutePath:%@",absolutePath);
    NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
 
 
 
21、文件擴展名
    NSString *Path = @"~/NSData.txt";
    NSLog(@"Extension:%@",[Path pathExtension]);

 
22、在已有字符串後面添加字符  
    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給出範圍和長度刪除字符

     NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
     [String1 deleteCharactersInRange:NSMakeRange(0, 5)];
     NSLog(@"String1:%@",String1);
 
 
 
2四、在已有字符串後面在所指定的位置中插入給出的字符串
 
    //-insertString: atIndex:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 insertString:@"Hi! " atIndex:0];
    NSLog(@"String1:%@",String1);
 

25、將已有的空符串換成其它的字符串
 
    //-setString:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 setString:@"Hello Word!"];
    NSLog(@"String1:%@",String1);
 
2六、按照所給出的範圍，和字符串替換的原有的字符
 
    //-setString:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
    NSLog(@"String1:%@",String1);
 
2七、判斷字符串內是否還包含別的字符串(前綴，後綴)
    //01：檢查字符串是否以另外一個字符串開頭- (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：查找字符串某處是否包含其它字符串 - (NSRange) rangeOfString: (NSString *) aString，這一點前面在串中搜索子串用到過;

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