compare:
NSString [a compare:b] NSOrderedSame NSOrderedAscending NSOrderedDescending
NSString 两个字符串的比较，用 a compare:b 来比，得出的结果分3种
1.26个字母比较 越靠后面 越大
NSString *a = @"qweqwe";
NSString *b = @"qweasd";
BOOL result = [a compare:b];
if (result == NSOrderedSame) { // NSOrderedSame =0 完全一样
NSLog(@"a =b");
}else if(result== NSOrderedAscending) // NSOrderedAscending =-1
NSLog(@"a< b");
else{ //NSOrderedDescending = +1
NSLog(@"a> b");
}
2011-07-05 15:04:33.951 Q[5180:207] a> b
2.比较数字或者符号，或者字母 什么都行
NSString*a =@"1.0.30qweqwe";
NSString *b= @"1.0.45qweasd";
BOOL result = [a compare:b];
if (result == NSOrderedSame) { // NSOrderedSame =0 完全一样
NSLog(@"a =b");
}else if(result== NSOrderedAscending) // NSOrderedAscending =-1
NSLog(@"a< b");
else{ //NSOrderedDescending = +1
NSLog(@"a> b");
}
2011-07-05 15:05:13.175Q[5209:207] a < b
3.不考虑大小写比较字符串
[a caseInsensitiveCompare:b]
- (void)viewDidLoad
{
NSString *a= @"i love my boyfriend.";
NSString *b= @"I Love My Boyfriend.";
NSLog(@" \n a: %@\n",a);
NSLog(@" \n b: %@\n",a);
BOOLresult = [acaseInsensitiveCompare:b]== NSOrderedSame;
｝
// result = (BOOL) YES;
4.不考虑大小写比较字符串
[a caseInsensitiveCompare:b]
- (void)viewDidLoad
{
NSString *a= @"i love my boyfriend.";
NSString *b= @"Little baby.";
NSLog(@" \n a: %@\n",a);
NSLog(@" \n b: %@\n",a);
BOOLresult = [acaseInsensitiveCompare:b]== NSOrderedAscending;
}
//result = (BOOL) YES;
5. 有选择的比较大小 [a compare:b options:NSCaseInsensitiveSearch|NSNumericSearch]
-(void)viewDidLoad
{
NSString *a= @"i love my boyfriend.";
NSString *b= @"I Love My Boyfriend.";
NSLog(@" \n a: %@\n",a);
NSLog(@" \n b: %@\n",b);
BOOLresult = [a compare:b options:NSCaseInsensitiveSearch|NSNumericSearch] == NSOrderedSame;
}
//result = (BOOL)YES;
NSCaseInsensitiveSearch 忽略大小写的比较字符串
NSNumericSearch 比较字符串的个数
NSLiteralSearch 区分大小写，进行完全比较