objective-c 如何检查 NSString 是否为数字
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How to check if NSString is numeric or not
提问by jaleel
Possible Duplicate:
iphone how to check that a string is numeric only
可能的重复：
iphone 如何检查字符串是否仅为数字
I have one NSString, then i want check the string is number or not.
我有一个 NSString，然后我想检查字符串是否为数字。
I mean
我的意思是
NSString *val = @"5555" ;
if(val isNumber ){
return true;
}else{
retun false;
}
How can I do this in Objective C?
我怎样才能在目标 C 中做到这一点？
回答by Dewayne Christensen
Use [NSNumberFormatter numberFromString: s]. It returns nil if the specified string is non-numeric. You can configure the NSNumberFormatter to define "numeric" for your particular scenario.
使用[NSNumberFormatter numberFromString: s]. 如果指定的字符串是非数字的，则返回 nil。您可以配置 NSNumberFormatter 为您的特定场景定义“数字”。
#import <Foundation/Foundation.h>
int
main(int argc, char* argv[])
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSLocale *l_en = [[NSLocale alloc] initWithLocaleIdentifier: @"en_US"];
NSLocale *l_de = [[NSLocale alloc] initWithLocaleIdentifier: @"de_DE"];
NSNumberFormatter *f = [[NSNumberFormatter alloc] init];
[f setLocale: l_en];
NSLog(@"returned: %@", [f numberFromString: @"1.234"]);
[f setAllowsFloats: NO];
NSLog(@"returned: %@", [f numberFromString: @"1.234"]);
[f setAllowsFloats: YES];
NSLog(@"returned: %@", [f numberFromString: @"1,234"]);
[f setLocale: l_de];
NSLog(@"returned: %@", [f numberFromString: @"1,234"]);
[l_en release];
[l_de release];
[f release];
[pool release];
}
回答by outis
You could use rangeOfCharacterFromSet::
你可以使用rangeOfCharacterFromSet:：
@interface NSString (isNumber)
-(BOOL)isInteger;
@end
@interface _IsNumber
+(void)initialize;
+(void)ensureInitialization;
@end
@implementation NSString (isNumber)
static NSCharacterSet* nonDigits;
-(BOOL)isInteger {
/* bit of a hack to ensure nonDigits is initialized. Could also
make nonDigits a _IsNumber class variable, rather than an
NSString class variable.
*/
[_IsNumber ensureInitialization];
NSRange nond = [self rangeOfCharacterFromSet:nonDigits];
if (NSNotFound == nond.location) {
return YES;
} else {
return NO;
}
}
@end
@implementation _IsNumber
+(void)initialize {
NSLog(@"_IsNumber +initialize\n");
nonDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
}
+(void)ensureInitialization {}
@end
