常用字符串函数/************************************* ************************************* ***** 一.NSString************************************* ************************************* *****//*----------------创建字符串的方法----------------*/ //1、创建常量字符串。

NSString *astring = @"Welcome to1000phone";//2、通过实例化方法initWithString:实例化一个字符串对象NSString *astring = [[NSString alloc] initWithString:@" I love iOS!"];NSLog(@"astring:%@",astring);
[astring release];//3、用标准c创建字符串: initWithCString:encoding:方法const char *cString = "I love iphone";NSString * aString = [[NSStringalloc]initWithCString:cStringencoding:NSUTF8StringEncoding];
NSLog(@"astring:%@",aString);
[aString release];或者:用initWithUTF8String:实例化一个字符串对象const char *p = " Welcome to Beijing!";
NSString *string = [[NSString alloc]initWithUTF8String:p];//4、创建格式化字符串:占位符(由一个%加一个字符组成)int age = 23;
NSString *astring = [[NSString alloc] initWithFormat:@”I am %d”,age]]; NSLog(@"astring:%@",astring);
[astring release];//5、通过静态方法创建字符串对象NSString * str1 = [NSString stringWithString:@"I love programming!"];
NSString * str2 = [NSString stringWithUTF8String:" I love programming!"]; NSString * str3 = [NSStringstringWithFormat:@"%@",@" I love programming!"];//6. 从文件读取字符串:initWithContentsOfFile:NSString *path = @"/Users/qianfeng/Desktop/StringAPI.pdf"; //文件路径NSString *astring = [[NSString alloc] initWithContentsOfFile:path];NSLog(@"astring:%@",astring);
[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"); }//1. isEqualToString 方法判断两个字符串是否相等相等返回 1 不等返回0NSString *astring01 = @"This is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01isEqualToString:astring02];NSLog(@"result:%d",result);//2. compare 方法(compare:返回的三种值分别是-1,0,1)//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 = [astring01compare:astring02] = = NSOrderedSame;//0 NSLog(@"result:%d",result);//NSOrderedAscending 判断两对象值的大小(按字母顺序进行比较,astring01 小于astring02 为真)
NSString *astring01 = @"This is a String!";
NSString *astring02 = @"this is a String!";BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;NSLog(@"result:%d",result); //
//NSOrderedDescending 判断两对象值的大小(按字母顺序进行比较,astring01 大于astring02 为真)NSString *astring01 = @"this is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;NSLog(@"result:%d",result);//3. 不考虑大小写比较字符串
NSString *astring01 = @"this is a String!";
NSString *astring02 = @"This is a String!";
BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;
NSLog(@"result:%d",result);
enum_NSComparisonResult {
NSOrderedAscending = -1, // astring01 小于astring02 NSOrderedSame, astring01 等于astring02 NSOrderedDescending astring01 大于astring02 };/*----------------改变字符串的大小写----------------*/ NSString *string1 = @"A String";NSString *string2 = @"String";//1. uppercaseString 小写转大写string1 指向的对象内容不会发生改变(会产生一个新的字符串对象,string 指向这个新的对象)
NSString *string = [string1 uppercaseString];
NSLog(@"string:%@",string);//2. lowercaseString 大写转小写string = [string1 lowercaseString];NSLog(@"string:%@",string);//3. capitalizedString 单词首字母大写其余小写,其他字符保持不变NSLog(@"string:%@",string);//首字母大小/*----------------搜索子串----------------*/ NSString *string1 = @"I love iOS very much!";
NSString *string2 = @"iOS";
NSRange range = [string1 rangeOfString:string2]; //NSRange 代表一个范围:子串string2 在长串string1 中的范围(位置和长度)
NSUIntegerlocation=range.location;
NSUIntegerlength= range.length;
NSString *astring = [NSStringstringWithFormat:@"Location:%lu,Leight:%l u",location, length];NSLog(@"astring:%@",astring);
[astring release];/*----------------抽取子串----------------*/
//1. -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);//2. -substringFromIndex: 从指定位置开始(包括指定位置的字符)提取,并包括之后的全部字符直到最后;NSString *string1 = @"This is a string";
NSString *string2 = [string1 substringFromIndex:3];NSLog(@"string2:%@",string2);//3. -substringWithRange: //在指定范围内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);/*------------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; (判断前缀)NSString *String1 = @"NSStringInformation.txt";
[String1 hasPrefix:@"NSString"] = = 1 ?NSLog(@"YES") : NSLog(@"NO"); //02:检查字符串是否以另一个字符串结尾- (BOOL) hasSuffix: (NSString *) aString; (判断后缀)
[String1 hasSuffix:@".txt"] = = 1 ?NSLog(@"YES") : NSLog(@"NO");/************************************* *****************************************二.NSMutableString************************************* ************************************* *****//*---------------给字符串分配预设空间大小----------------*/ //stringWithCapacity:NSMutableString *string;
string = [NSMutableString stringWithCapacity:20];//预设一个20 字节的字符串空间
string.string = @”Welcome to qianfeng”;/*---------------增加字符串----------------*/
//1. appendString: appendFormat: 追加,在后面追加字符串NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];//[String1 appendString:@", I will be adding some characters"];
[String1 appendFormat:[NSStringstringWithFormat:@", I will be adding some characters"]];
NSLog(@"String1:%@",String1);//2. -insertString: atIndex: 在指定位置插入字符串NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 insertString:@"Hi! " atIndex:0];
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: 在指定范围内删除字符串
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)]; NSLog(@"String1:%@",String1);/*--------修改字符串------*/ //-setString: 修改字符串NSMutableString *String1 = [[NSMutableString alloc]initWithString:@"This is a NSMutableString"];
[String1setString:@"Hello Word!"];
NSLog(@"String1:%@",String1);/*--------在指定范围内,替换的原有的字符------*/ // replaceCharactersInRange: withString: 替换NSMutableString *String1 = [[NSMutableString alloc]initWithString:@"This is a NSMutableString"];
[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];NSLog(@"String1:%@",String1);/************************************* ************************************* **** NSArray************************************* ************************************* *****//*---------------------------创建数组------------------------------*/NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSArray * array1 = [[NSArrayalloc]initWithArray:array]; NSArray * array2 = [NSArray arrayWithArray:array]; NSArray *array3 = [[NSArray arrayWithObjects: @"One",@"Two",@"Three",@"Four",nil]; [array release]; [array1 release];//- (NSUInteger) Count;数组所包含对象(元素)个数; NSLog(@"count:%d",[array count]);
//- (id) objectAtIndex: (NSUInteger) index;获取指定索引处的对象(元素);NSLog(@"object :%@",[arrayobjectAtIndex:2]);/*查找:根据元素找到对应的索引*/ NSArray*array=[[NSArrayalloc]initWithObje cts:@"one",@"two",@"three",@"one ", nil];
//返回找到的第一个的索引, 一切操作不要越界
NSUInteger index = [array indexOfObject:@"one"];//在指定范围内查找
index = [array indexOfObject:@"one"inRange:NSMakeRange(1, 3)]; if (index != NSNotFound) {//找不到返回NSNotFound NSLog(@"index = %ld",index); }/*数组的抽取*/
NSArray * array1 = [array objectsAtIndexes:[NSIndexSetindexSetWithIndexesInRange:NSMakeRange( 1, 3)]];
//NSIndexSet 数字集合类
//[NSIndexSet indexSetWithIndexesInRange:NSMakeRange( 1, 3)];创建一个数字集合对象//该集合成员是数字1,2,3;/*枚举器*///创建一个正序枚举器
NSEnumerator * enume1 = [array objectEnumerator]; //枚举器是读数据的while (obj = [enume1 nextObject]){ NSLog(@"%@",obj);}//快速枚举(正序)NSArray *array = [NSArray arrayWithObjects: @"a",@"b",@"c",@"d",nil];for(id obj in array) {NSLog(@"obj:%@",obj);}//创建一个逆序枚举器
NSEnumerator * enume2 = [array reverseObjectEnumerator]; while (obj = [enume2 nextObject]) {NSLog(@"obj = %@",obj); }/*---------------------------字符串分割到数组------------------------------*/NSString * str = @" Yes,I am a good man ";
//以字符串整体作为分割条件
NSArray * array = [str componentsSeparatedByString:@" "];//以@” ” 作为分割条件
NSArray*array1 = [str componentsSeparatedByCharactersInSet:[NS CharacterSet characterSetWithCharactersInString:@" ,"]];//以字符作为分割条件//NSCharacterSet 字符集合
//[NSCharacterSet characterSetWithCharactersInString:@" ,"];把字符串@" ,"转化为一个字符集合
//这个集合的成员就是字符' '和字符',';
//返回值是NSArray 不要写成NSMuatbaleArray/*---------------------------数组元素拼接成字符串------------------------------*/NSString * ptr = [array componentsJoinedByString:@"###"];//把数组元素拼接成字符串
NSLog(@”ptr= %@”,ptr);/************************************* ************************************* **** NSMutableArray************************************* ************************************* *****//*创建一个可变数组(继承于NSArray)*/ NSMutableArray *array = [[NSMutableArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSMutableArray * array1 = [[NSMutableArray alloc]initWithArray:array]; NSMutableArray * array2 = [NSMutableArray arrayWithArray:array]; NSMutableArray *array3 = [[NSMutableArray arrayWithObjects: @"One",@"Two",@"Three",@"Four",nil]; [array release]; [array1 release];//把不可变转化为一个新的可变数组
NSArray *array = [NSArray arrayWithObjects: @"a",@"b",@"c",@"d",nil]; NSMutableArray * array1 = [NSMutableArrayarrayWithArray:array];//增add (insert)
[arrayaddObject:@"four"];//在最后增加
[array insertObject:@"iOS" atIndex:1];//在指定索引插入一个元素//删除(remove)
[array removeObjectAtIndex:1];//根据索引删除元素
[array removeObject:@"one"];//删除数组元素:有几个删几个
[array removeObject:@"one"inRange:NSMakeRange(0, 2)]; //在指定范围内删除//替换(replace):修改
[array replaceObjectAtIndex:0withObject:@"qianfeng"];//交换(exchange)
[array exchangeObjectAtIndex:1 withObjectAtIndex:2];/*可变数组排序*///创建一个空的可变数组
//(首先设计一个Dog 类)
NSMutableArray * array = [[NSMutableArray alloc]init]; while (i++ < 5) {Dog * dog = [[Dogalloc]initWithAge:arc4random()%10]; [array addObject:dog];
}[arraysortUsingSelector:@selector(youngThanAge:) ];//sortUsingSelector 这是一个排序方法;已经实现了, //但是需要我们提供一个准则(就是一个函数)这个准则是(升序)左边大于右边进行交换或者是(降序)左边小于右边进行交换//数组的元素是哪个类?那么这个准则就写在哪个类中
//这就是一个准则左边大于右边进行交换
//升序
-(BOOL)olderThanAge:(Dog *)_dog
{ return [self age] > [_dog age];}/************************************* ************************************ NSDictionary************************************* ************************************* **///内容可以是任意的对象指针//内容是一些键值对key à value //必须成对出现一个key 对应一个value //key 是唯一的不能出现多个相同的key1.创建一个不可变字典(1)
NSDictionary*dict=[[NSDictionaryalloc]initWithObjectsAndKeys:@"1",@"one", @"2",@"two",@"3",@"three",@"4", @"four",@"5",@"five", nil];//
创建一个不可变字典(2)
NSDictionary * dict1 = [NSDictionary dictionaryWithDictionary:dict]; 创建一个不可变字典(3)
NSArray * values =[[NSArrayalloc]initWithObjects:@"1",@"2",@"3",@"4",nil]; NSArray*keys=[[NSArrayalloc]initWithObjects:@"one",@"two",@"thre e",@"four", nil];
NSDictionary* dict2 = [[NSDictionary alloc]initWithObjects:values forKeys:keys];//键值对的个数
NSLog(@"count= %ld",[dict2 count]);//查找通过key 找到对应值
NSLog(@"%@",[dictobjectForKey:@"four"]); 词典类的存在就是为了解决在大量数据中查找方便,因为它是通过key 直接找到value 所以速度很快,避免一个个的遍历寻找造成的效率低下,善用字典类会帮你的程序提速。