ObjectiveC开发教程--字符串的基本操作处理方法

 

//一、NSString
/*----------------创建字符串的方法----------------*/

//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!;
[astring release];
NSLog(@astring:%@,astring);

//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);




/*----------------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];


/*----------------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];


/*----------------比较两个字符串----------------*/


//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)


//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。


/*----------------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


/*---------------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];


/*----------------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);


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


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


/*******************************************************************************************
NSMutableString
*******************************************************************************************/


/*---------------给字符串分配容量----------------*/
//stringWithCapacity:
NSMutableString *String;
String = [NSMutableString stringWithCapacity:40];


/*---------------在已有字符串后面添加字符----------------*/


//appendString: and appendFormat:
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);
*/


/*--------在已有字符串中按照所给出范围和长度删除字符------*/
/*
//deleteCharactersInRange:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@This is a NSMutableString];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)];
NSLog(@String1:%@,String1);


/*--------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);


/*--------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);


/*--------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);


/*-------------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);