字符串处理
//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"); //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;