Objective-C:在字符串中查找数字

I have a string that contains words as well as a number. How can I extract that number from the string?

我有一个包含单词和数字的字符串。如何从字符串中提取那个数字?

NSString *str = @"This is my string. #1234";

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.

我想去掉1234作为int类型，每次搜索时字符串都会有不同的数字和单词。

Ideas?

想法吗?

7 个解决方案

#1

Here's an NSScanner based solution:

这里有一个基于NSScanner的解决方案:

// 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];

(Some of the many) assumptions made here:

(其中一些)这里的假设:

Number digits are 0-9, no sign, no decimal point, no thousand separators, etc. You could add sign characters to the NSCharacterSet if needed.
数字是0-9，没有符号，没有小数点，没有千位分隔符等等。如果需要，可以在ns字符集中添加符号字符。
There are no digits elsewhere in the string, or if there are they are after the number you want to extract.
在字符串的其他地方没有数字，或者如果有，它们在您想要提取的数字之后。
The number won't overflow int.
数字不会溢出int。

Alternatively you could scan direct to the int:

也可以直接扫描到int:

[scanner scanUpToCharactersFromSet:numbers intoString:NULL];
int number;
[scanner scanInt:&number];

If the # marks the start of the number in the string, you could find it by means of:

如果#标记字符串中数字的开始，您可以通过以下方法找到它:

[scanner scanUpToString:@"#" intoString:NULL];
[scanner setScanLocation:[scanner scanLocation] + 1];
// Now scan for int as before.

#2

Self contained solution:

自包含的解决方案:

+ (NSString *)extractNumberFromText:(NSString *)text
{
  NSCharacterSet *nonDigitCharacterSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
  return [[text componentsSeparatedByCharactersInSet:nonDigitCharacterSet] componentsJoinedByString:@""];
}

Handles the following cases:

处理以下情况:

@"1234" → @"1234"
@“1234”→@“1234”
@"001234" → @"001234"
@“001234”→@“001234”
@"leading text get removed 001234" → @"001234"
@“领先的文本删除001234”→@“001234”
@"001234 trailing text gets removed" → @"001234"
@“001234后文本被删除”→@“001234”
@"a0b0c1d2e3f4" → @"001234"
@“a0b0c1d2e3f4”→@“001234”

Hope this helps!

希望这可以帮助!

#3

Try this answer from Stack Overflow for a nice piece of C code that will do the trick:

尝试一下Stack Overflow的答案，找到一段不错的C代码，就可以做到:

for (int i=0; i<[str length]; i++) {
        if (isdigit([str characterAtIndex:i])) {
                [strippedString appendFormat:@"%c",[str characterAtIndex:i]];
        }
}

#4

You could use the NSRegularExpression class, available since iOS SDK 4.

您可以使用NSRegularExpression类，从iOS SDK 4开始就可以使用。

Bellow a simple code to extract integer numbers ("\d+" regex pattern) :

使用简单的代码提取整数(“\d+”regex模式):

- (NSArray*) getIntNumbersFromString: (NSString*) string {

  NSMutableArray* numberArray = [NSMutableArray new];

  NSString* regexPattern = @"\\d+";
  NSRegularExpression* regex = [[NSRegularExpression alloc] initWithPattern:regexPattern options:0 error:nil];

  NSArray* matches = [regex matchesInString:string options:0 range:NSMakeRange(0, string.length)];
  for( NSTextCheckingResult* match in matches) {
      NSString* strNumber = [string substringWithRange:match.range];
      [numberArray addObject:[NSNumber numberWithInt:strNumber.intValue]];
  }

  return numberArray; 
}

#5

By far the best solution! I think regexp would be better, but i kind of sux at it ;-) this filters ALL numbers and concats them together, making a new string. If you want to split multiple numbers change it a bit. And remember that when you use this inside a big loop it costs performance!

到目前为止，这是最好的解决方案!我认为regexp会更好，但是我有点喜欢它;-)它过滤所有的数字并将它们合并在一起，形成一个新的字符串。如果你想分割多个数字，就改变一点。记住，当你在一个大循环中使用它时，它会降低性能!

    NSString *str= @"bla bla bla #123 bla bla 789";
    NSMutableString *newStr = [[NSMutableString alloc] init];;
    int j = [str length];
    for (int i=0; i<j; i++) {       
        if ([str characterAtIndex:i] >=48 && [str characterAtIndex:i] <=59) {
            [newStr appendFormat:@"%c",[str characterAtIndex:i]];
        }               
    }

    NSLog(@"%@  as int:%i", newStr, [newStr intValue]);

#6

NSPredicate is the Cocoa class for parsing string using ICU regular expression.

NSPredicate是使用ICU正则表达式解析字符串的Cocoa类。

#7

Swift extension for getting number from string

从字符串中获取数字的快速扩展

extension NSString {

func getNumFromString() -> String? {

    var numberString: NSString?
    let thisScanner = NSScanner(string: self as String)
    let numbers = NSCharacterSet(charactersInString: "0123456789")
    thisScanner.scanUpToCharactersFromSet(numbers, intoString: nil)
    thisScanner.scanCharactersFromSet(numbers, intoString: &numberString)
    return numberString as? String;
}
}

#1