Objective-C:在字符串中查找数字 [英] Objective-C: Find numbers in string
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问题描述
我有一个包含单词和数字的字符串。如何从字符串中提取该数字?
I have a string that contains words as well as a number. How can I extract that number from the string?
NSString *str = @"This is my string. #1234";
我希望能够将1234剥离为int。每次搜索时,字符串都会有不同的数字和单词。
I would like to be able to strip out 1234 as an int. The string will have different numbers and words each time I search it.
想法?
推荐答案
这是 NSScanner 基于解决方案:
// Input
NSString *originalString = @"This is my string. #1234";
// Intermediate
NSString *numberString;
NSScanner *scanner = [NSScanner scannerWithString:originalString];
NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
// Throw away characters before the first number.
[scanner scanUpToCharactersFromSet:numbers intoString:NULL];
// Collect numbers.
[scanner scanCharactersFromSet:numbers intoString:&numberString];
// Result.
int number = [numberString integerValue];
(这里有一些)假设:
- 数字位数为0-9,无符号,无小数点,无千位分隔符等。如果需要,可以在NSCharacterSet中添加符号字符。
- 字符串中的其他位置没有数字,或者 后要提取的数字。
- 数字不会溢出
int
。
- Number digits are 0-9, no sign, no decimal point, no thousand separators, etc. You could add sign characters to the NSCharacterSet if needed.
- There are no digits elsewhere in the string, or if there are they are after the number you want to extract.
- The number won't overflow
int
.
或者你可以直接扫描到 int
:
Alternatively you could scan direct to the int
:
[scanner scanUpToCharactersFromSet:numbers intoString:NULL];
int number;
[scanner scanInt:&number];
如果#
标志着字符串中的数字,您可以通过以下方式找到它:
If the #
marks the start of the number in the string, you could find it by means of:
[scanner scanUpToString:@"#" intoString:NULL];
[scanner setScanLocation:[scanner scanLocation] + 1];
// Now scan for int as before.
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