oc中字符串的一些简单用法

//

// main.m

// 6NSString

//

// Created by 4_5 on 13-8-18.

// Copyright (c) 2013年
南阳理工学院. All rights reserved.

//

//字符串为我们封装了许多可以直接拿来用的方法
比如， 获取字符串的长度，字符串的比较，字符串的拼接，查找，截取等

#import <Foundation/Foundation.h>

int main(int argc,
const
char * argv[])
{

@autoreleasepool {

NSString *string1 =@
"999" ;

NSString *string2 =
@"888" ;

int int1 = [string1
intValue] ;
//把字符串型的转换成int型的

int int2 = [string2
intValue] ;

int result ;
result =int1 - int2 ;

NSString *resultString = [NSString
stringWithFormat:@"%d",result] ;

NSLog(@"result = %d,resultString = %@",result,resultString);

unsigned
long strlength1 = [string1
length] ;//如果定义成int型的就会出现警告
因为length的返回类型就是unsigned
也可以写成 NSUInteger

unsigned
long strlength2 = [string2
length] ;

unsigned
long resultlength = [resultString
length] ;

NSLog(@"strlength1 = %ld,strlength2 = %ld,resultlength = %ld",strlength1 ,strlength2,resultlength)
;
}

NSString *str3 =
@"hello world" ;

NSString *str4 = [NSString
stringWithFormat:@"hello world"] ;

NSString *str5 = [NSString
stringWithString:@"hello world"] ;//是一个浅拷贝，源对象与拷贝对象共用一个实体
，只是变量名不同而已

if([str3
isEqualToString:str4])
{

NSLog(@"str3 and str4字符串内容相等");
}

if (str3==str4) {

NSLog(@"str3 and str4字符串指针相等");
}

if ([str3
isEqualToString:str5]) {

NSLog(@"str3 and str5字符串内容相等");
}

if (str3==str5) {

NSLog(@"str3 and str5字符创指针相等") ;

}

//字符串的比较

//-(NSComparisonResult*)compare:(NSString*)astring
改方法比较字符串时区分大小写

// -(NSComparisonResult*)compare:(NSString *)astring options:(NSStringCompareOptions)mask

//改方法在比较字符串是可以加一些额外控制选项

//NSComparisonResult是一个枚举类型的

NSString *str6 =
@"hello" ;

NSString *str7 =
@"Hello" ;

switch ([str6
compare:str7]) {

case
NSOrderedAscending:

NSLog(@"升序是%ld",NSOrderedAscending)
;

break;

case
NSOrderedDescending:

NSLog(@"降序是%ld",NSOrderedDescending)
;

break ;

case
NSOrderedSame:

NSLog(@"相等时%ld",NSOrderedSame)
;

break ;

default:

break;
}

//字符串的查找与截取

NSString *str8 =
@"ios-45.doc" ;

if ([str8
hasPrefix:@"ios"]) {

NSLog(@"本字符串是以ios开头的");
}

if ([str8
hasSuffix:@".doc"]) {

NSLog(@"本字符串是以doc结尾的");
}

char c = [str8
characterAtIndex:2] ;//索引从0开始

NSString *fromString = [str8
substringFromIndex:5] ;//从第5个到最后

NSString *toString = [str8
substringToIndex:5] ;//从开始到第5个不包括第五个

NSString *rangeString = [str8
substringWithRange:NSMakeRange(3,
5)] ;//从第3个数取出5个字符

NSLog(@"c= %c,from = %@,to = %@,range = %@",c,fromString,toString,rangeString) ;

//字符串的替换,可变数组可以在原数组的基础上进行修改，不可变数组返回的是一个新的数组，原数组没有改变

NSString *oldstring =
@"hello" ;

NSString *newString = [oldstring
stringByReplacingOccurrencesOfString:@"h"
withString:@"g"] ;

NSLog(@"newString = %@",newString);

return
0;
}