# NSScanner class reference

eric@skatter.usask.ca
rfm@gnu.org
Generated at 2025-09-10 09:16:48 +0000
1996,1999 Free Software Foundation, Inc.
Software documentation for the NSScanner class
Foundation/NSScanner.h
NSCopying

The `NSScanner` class cluster (currently a single class in GNUstep) provides a mechanism to parse the contents of a string into number and string values by making a sequence of scan operations to step through the string retrieving successive items.

You can tell the scanner whether its scanning is supposed to be case sensitive or not, and you can specify a set of characters to be skipped before each scanning operation (by default, whitespace and newlines).

localizedScannerWithString:
aString
Returns an NSScanner instance set up to scan aString (using -initWithString: and with a locale set the default locale (using -setLocale:
scannerWithString:
aString
Create and return a scanner that scans aString.
Uses -initWithString: and with no locale set.
caseSensitive
If the scanner is set to be case-sensitive in its scanning of the string (other than characters to be skipped), this method returns `YES`, otherwise it returns `NO`.
The default is for a scanner to not be case sensitive.
charactersToBeSkipped
Returns a set of characters containing those characters that the scanner ignores when starting any scan operation. Once a character not in this set has been encountered during an operation, skipping is finished, and any further characters from this set that are found are scanned normally.
The default for this is the whitespaceAndNewlineCharacterSet.
initWithString:
aString
Initialises the scanner to scan aString. The GNUstep implementation may make an internal copy of the original string - so it is not safe to assume that if you modify a mutable string that you initialised a scanner with, the changes will be visible to the scanner.
Returns the scanner object.
isAtEnd
Returns `YES` if no more characters remain to be scanned.
Returns `YES` if all characters remaining to be scanned are to be skipped.
Returns `NO` if there are characters left to scan.
locale
Returns the locale set for the scanner, or `nil` if no locale has been set. A scanner uses it's locale to alter the way it handles scanning - it uses the NSDecimalSeparator value for scanning numbers.
scanCharactersFromSet:
aSet
intoString:
value
After initial skipping (if any), this method scans any characters from aSet, terminating when a character not in the set is found.
Returns `YES` if any character is scanned, `NO` otherwise.
If value is not null, any character scanned are stored in a string returned in this location.
scanDecimal:
value
Not implemented.
scanDouble:
value
After initial skipping (if any), this method scans a double value, placing it in doubleValue if that is not null. Returns `YES` if anything is scanned, `NO` otherwise.
On overflow, HUGE_VAL or - HUGE_VAL is put into doubleValue
On underflow, 0.0 is put into doubleValue
Scans past any excess digits
scanFloat:
value
After initial skipping (if any), this method scans a float value, placing it in floatValue if that is not null. Returns `YES` if anything is scanned, `NO` otherwise.
On overflow, HUGE_VAL or - HUGE_VAL is put into floatValue
On underflow, 0.0 is put into floatValue
Scans past any excess digits
scanHexDouble:
result
Not implemented
scanHexFloat:
result
Not implemented
scanHexInt:
value
After initial skipping (if any), this method scans a hexadecimal integer value (optionally prefixed by "0x" or "0X"), placing it in intValue if that is not null.
Returns `YES` if anything is scanned, `NO` otherwise.
On overflow, INT_MAX or INT_MIN is put into intValue
Scans past any excess digits
scanHexLongLong:
value
After initial skipping (if any), this method scans a hexadecimal long long value (optionally prefixed by "0x" or "0X"), placing it in longLongValue if that is not null.
Returns `YES` if anything is scanned, `NO` otherwise.
On overflow, ULLONG_MAX or ULLONG_MAX is put into longLongValue
Scans past any excess digits
scanInt:
value
After initial skipping (if any), this method scans a integer value, placing it in intValue if that is not null.
Returns `YES` if anything is scanned, `NO` otherwise.
On overflow, INT_MAX or INT_MIN is put into intValue
Scans past any excess digits
scanInteger:
value
Not implemented
scanLocation
Returns the current position that the scanner has reached in scanning the string. This is the position at which the next scan operation will begin.
scanLongLong:
value
After initial skipping (if any), this method scans a long decimal integer value placing it in longLongValue if that is not null.
Returns `YES` if anything is scanned, `NO` otherwise.
On overflow, LLONG_MAX or LLONG_MIN is put into longLongValue
Scans past any excess digits
scanRadixUnsignedInt:
value
After initial skipping (if any), this method scans an unsigned integer placing it in value if that is not null. If the number begins with "0x" or "0X" it is treated as hexadecimal, otherwise if the number begins with "0" it is treated as octal, otherwise the number is treated as decimal.
Returns `YES` if anything is scanned, `NO` otherwise.
On overflow, UINT_MAX is put into value
Scans past any excess digits
scanRadixUnsignedLongLong:
value
After initial skipping (if any), this method scans an unsigned long long integer placing it in value if that is not null. If the number begins with "0x" or "0X" it is treated as hexadecimal, otherwise if the number begins with "0" it is treated as octal, otherwise the number is treated as decimal.
Returns `YES` if anything is scanned, `NO` otherwise.
On overflow, ULLONG_MAX is put into value
Scans past any excess digits
scanString:
string
intoString:
value
After initial skipping (if any), this method scans for string and places the characters found in value if that is not null.
Returns `YES` if anything is scanned, `NO` otherwise.
scanUpToCharactersFromSet:
aSet
intoString:
value
After initial skipping (if any), this method scans characters until it finds one in set. The scanned characters are placed in stringValue if that is not null.
Returns `YES` if anything is scanned, `NO` otherwise.
scanUpToString:
string
intoString:
value

After initial skipping (if any), this method scans characters until it finds string. The scanned characters are placed in value if that is not null. If string is not found, all the characters up to the end of the scanned string will be returned.

Returns `YES` if anything is scanned, `NO` otherwise.

NB. If the current scanner location points to a copy of string, or points to skippable characters immediately before a copy of string then this method returns `NO` since it finds no characters to store in value before it finds string.

To count the occurrences of string, this should be used in conjunction with the -scanString:intoString: method.

NSString *ch = @"["; unsigned total = 0;

[scanner scanUpToString: ch intoString: NULL]; while ([scanner scanString: ch intoString: NULL] == YES) { total++; [scanner scanUpToString: ch intoString: NULL]; } NSLog(@"total %d", total);
setCaseSensitive:
flag
Sets the case sensitivity of the scanner.
Case sensitivity governs matching of characters being scanned, but does not effect the characters in the set to be skipped.
The default is for a scanner to not be case sensitive.
setCharactersToBeSkipped:
aSet
Sets the set of characters that the scanner will skip over at the start of each scanning operation to be skipSet. Skipping is performed by literal character matching - the case sensitivity of the scanner does not effect it. If this is set to `nil`, no skipping is done.
The default for this is the whitespaceAndNewlineCharacterSet.
setLocale:
localeDictionary
This method sets the locale used by the scanner to aLocale. The locale may be set to `nil`.
setScanLocation:
anIndex
This method sets the location in the scanned string at which the next scan operation begins. Raises an NSRangeException if index is beyond the end of the scanned string.
string
Returns the string being scanned.