从字符串中删除前导 0，目标 C [英] remove leading 0 from a string, objective C

问题描述

可能的重复:
从字符串中删除前导零

我需要从字符串的开头删除 0 并防止用户输入数字时出现前导 0，我该怎么做?

I need to remove 0 from the beginning of a string and prevent leading 0s when user input the number, how can I do it?

例如:用户输入:000090显示:90

For example: user input: 000090 display: 90

谢谢！

推荐答案

一种方法是使用 NSScanner:

NSString *string = @"000090";
NSCharacterSet *nonzeroNumberCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@"123456789"];
NSScanner *scanner = [NSScanner scannerWithString:string];
[scanner scanUpToCharactersFromSet:nonzeroNumberCharacterSet intoString:nil];
NSString *remainder = nil;
NSCharacterSet *emptyCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@""];
[scanner scanUpToCharactersFromSet:emptyCharacterSet intoString:&remainder];

此时remainder等于@"90".

等效地，可以替换线条

NSCharacterSet *nonzeroNumberCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@"123456789"];
NSScanner *scanner = [NSScanner scannerWithString:string];

与

NSCharacterSet *zeroNumberCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@"0"];
[scanner scanCharactersFromSet:zeroNumberCharacterSet intoString:nil];

扫描所有零而不是扫描到第一个非零数字.

to scan past all the zeros rather than to scan until the first non-zero number.

这种方法的一个缺点是，如果原始字符串是 @"000000000"，则结果字符串将为空.

One drawback of this approach is that if the original string is @"000000000", the resulting string will be empty.

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