I have an NSString which is a mathematical expression. I have operators (+,-,*,/) and operands (digits from 0 to 9,integers,decimals etc). I want to convert this NSString into NSArray. For example if my NSString is "7.9999-1.234*-9.21". I want NSArray having elements 7.9999,-,1.234,*,-,9.21 in the same order. How can I accomplish this?
I have tried a code. It dosent work in all scenarios though. Here It is:
code:
NSString *str=#"7.9999-1.234*-9.21";
NSMutableArray *marray=[[NSMutableArray alloc] init];
for(i=0;i<6;i++)
{
[marray addObject:[NSNull null]];
}
NSMutableArray *operands=[[NSMutableArray alloc] initWithObjects:#"7.9999",#"1.234",#"9.21",nil];
NSMutableArray *operators=[[NSMutableArray alloc] initWithObjects:#"-",#"*",#"-",nil];
for(i=0,j=0,k=0,l=0;i<=([str length]-1),j<[operands count],k<[operators count],l<[marray count];i++)
{
NSString *element=[[NSString alloc] initWithFormat:#"%c",[str characterAtIndex:i]];
BOOL res=[element isEqualToString:#"+"]||[element isEqualToString:#"-"]||[element isEqualToString:#"*"]||[element isEqualToString:#"/"];
if(res==0)
{
[marray replaceObjectAtIndex:l withObject:[operands objectAtIndex:j]];
}
else
{
l++;
[marray replaceObjectAtIndex:l withObject:[operators objectAtIndex:k]];
k++,l++,j++;
}
}
for(i=0;i<6;i++)
{
NSLog(#"%#",[marray objectAtIndex:i]);
}
Here str is the string to be converted. My array is the array obtained by converting the string str. When I execute this code I get the following on console:
7.9999
-
1.234
*
<null>
-
You should use NSScanner, scanning up to your operator characters, then when you find one, save the scanned string and then save the operator into the array and skip the operator (setScanLocation:). Continue doing this till you get to the end of the string (in a loop, one iteration for each operator).
NSArray * marray = [str componentsSeparatedByCharactersInSet:
[NSCharacterSet characterSetWithCharactersInString:#"+-*/"]
];
ThankYou #Wain and #Hinata Hyuga.I figured out a code that would work to convert any string to array with the help of your suggestions.
Here is the code
NSMutableArray *convArray=[[NSMutableArray alloc] init];
NSScanner *scanner = [NSScanner scannerWithString:inputString];
NSCharacterSet *opSet=[NSCharacterSet characterSetWithCharactersInString:#"+-/*"];
[scanner setCharactersToBeSkipped:opSet];
int i;
for(i=0;i<[inputString length];)
{
if([inputString characterAtIndex:i]=='+'||[inputString characterAtIndex:i]=='-'||[inputString characterAtIndex:i]=='*'||[inputString characterAtIndex:i]=='/')
{
[convArray addObject:[[NSString alloc] initWithFormat:#"%c",[inputString characterAtIndex:i]]];
i++;
}
else
{
NSString *oprnd;
[scanner scanUpToCharactersFromSet:opSet intoString:&oprnd];
[convArray addObject:oprnd];
i=i+[inputString rangeOfString:oprnd].length;
}
}
return convArray;
Related
I am generating a random equation say like 2*3+4..... and using DDMathparser to evaluate it. Here I have a class method which is supposed to return a random equation(stored inside a mutable array) only if it evaluates to a integer.
however it keeps returning Null and i can't figure out why. Please help me out.!
#import "Equation.h"
#import "DDMathParser.h"
#implementation Equation
-(NSMutableArray*)randEquation{
NSMutableArray* usableEquation=[[NSMutableArray alloc]init];
while(1){
NSArray *nums = #[#"1", #"2", #"3", #"4", #"5",#"6",#"7",#"8",#"9"];
unsigned index1=arc4random()%9;
NSString* num = [NSString stringWithFormat:#"%#", [nums objectAtIndex:index1]];
NSArray *symbols = #[#"+", #"-", #"*", #"/"];
unsigned index=arc4random()%4;
NSString* symb = [NSString stringWithFormat:#"%#", [symbols objectAtIndex:index]];
NSMutableArray *arrayOfSymbolsAndNumbers = [[NSMutableArray alloc] init];
for( int i=0;i<=10;i++){
if (i%2==0) {
[arrayOfSymbolsAndNumbers addObject:num];
}
else{
[arrayOfSymbolsAndNumbers addObject:symb];
}
}
NSMutableString *stringOfSymbolsAndNumbers=[[NSMutableString alloc]init];
for (NSObject * obj in arrayOfSymbolsAndNumbers)
{
[stringOfSymbolsAndNumbers appendString:[obj description]];
}
usableEquation=arrayOfSymbolsAndNumbers;
NSNumber *result=[stringOfSymbolsAndNumbers numberByEvaluatingString];
float resultFloat = [result floatValue];
float checker=resultFloat;
if (floor(checker)==checker) {
break;
}
else{
continue;
}
}
return usableEquation;
}
#end
NSLog(#"The content of array is%#",[equation randEquation]);
Based on your code, for this log to output The content of array is(null) means that equation is nil. Your randEquation (while not efficient) looks ok, the problem is that you haven't created the equation instance when you run the log statement.
I am trying to parse a large string in order to isolate words and all punctuation. Java has the following constructor for its StringTokenizer class.
public StringTokenizer(String str, String delim, boolean returnDelims)
Notice the last parameter. If that is true, each delimiter is also returned as a token.
Is there a class in Obj-C that mimics this Java functionality? I have been able to parse the string, but I lose my delimiters in the process and those delimiters determine what I do next.
According to the CFStringTokenizer reference, it tokenizes into "words, sentences, and paragraphs". I need more granularity than that.
Appreciate the help.
You can just use the componentsSeparatedByString: method of NSString and then NSMutableArray to insert the delimiters between the substrings:
NSString *s = #"abc,def,ghi,jkl";
NSString *delim = #",";
NSArray *arr = [s componentsSeparatedByString:delim];
NSMutableArray *res = [NSMutableArray array];
[res addObject:arr[0]];
for (NSInteger i = 1; i < arr.count; i++) {
[res addObject:delim];
[res addObject:arr[i]];
}
NSLog(#"%#", res);
Here is a sample category on NSScanner that may get you started:
#implementation NSScanner (Tokenizer)
+ (NSArray *)tokenize(NSString *str,NSString *delim,BOOL returnDelims)
{
NSScanner *scanner=[NSScanner scannerWithString:str];
NSString *delimiters=[NSCharacterSet characterSetWithCharactersInString:#",.!;"];
NSMutableArray *ma=[NSMutableArray array];
NSString *s;
while(![scanner isAtEnd])
{
if([scanner scanUpToCharactersFromSet:delim intoString:&s])
{
[ma addObject:s];
}
if([scanner scanCharactersFromSet:delim intoString:&s])
{
if(returnDelims) [ma addObject:s];
}
}
return ma;
}
#end
This isn't a complete implementation, it doesn't deal with whitespace or enforcing a specific order in the array. But it should give you an idea.
I'v been trying to split string to array of components by number, but have no idea how to do it. I know that each components lenght is 9 except the last one. But there is no separation between them. Maybe anyone would know how could i make this split possible?
string : E44000000R33000444V33441
And i'd like to get array with: E44000000 R33000444 V33441
in past I'v used this method, but i guess there should be a way to separate by constant number. Any ideas
NSArray *myWords = [message componentsSeparatedByString:#";"];
Please try the below code.
NSString *stringTest = #"E44000000R33000444V33441323";
NSMutableArray *arrayTest = [NSMutableArray array];
while([stringTest length] > 8) {
[arrayTest addObject:[NSString stringWithString:[stringTest substringToIndex:9]]];
stringTest = [stringTest substringFromIndex:9];
}
NSLog(#"arrayTest - %#", arrayTest);
Try this one..
NSString *mainString=#"E44000000R33000444V";
NSMutableArray *brokenString=[NSMutableArray new];
int start=0;
for (; start<mainString.length-9; start+=9) {
[brokenString addObject:[mainString substringWithRange:NSMakeRange(start, 9)]];
}
[brokenString addObject:[mainString substringFromIndex:start]];
NSLog(#"->%#",brokenString);
Output is :
->(
E44000000,
R33000444,
V
)
I investigated the NSString, and i didn't found any function like that. But you can create a category of NSString and put this function in that category and you can use as a NSString instance method.
- (NSArray *) componentSaparetedByLength:(NSUInteger) length{
NSMutableArray *array = [NSMutableArray new];
NSRange range = NSMakeRange(0, length);
NSString *subString = nil;
while (range.location + range.length <= self.length) {
subString = [self substringWithRange:range];
[array addObject:subString];
//Edit
range.location = range.length + range.location;
//Edit
range.length = length;
}
if(range.location<self.length){
subString = [self substringFromIndex:range.location];
[array addObject:subString];
}
return array;
}
You can get the substring upto the characters which you want in a loop(string length) & pass the next index for getting the next substring. After getting each substring you can add it to the array.
Used SubstringToIndex & SubstringFromIndex functions to get the substring.
Also not an requirement here, I want to propose a solution that is capable of handling characters from more sophisticated script systems, like surrogate pairs, base characters plus combining marks, Hangul jamo, and Indic consonant clusters.
#interface NSString (Split)
-(NSArray *)arrayBySplittingWithMaximumSize:(NSUInteger)size
options:(NSStringEnumerationOptions) option;
#end
#implementation NSString (Split)
-(NSArray *)arrayBySplittingWithMaximumSize:(NSUInteger)size
options:(NSStringEnumerationOptions) option
{
NSMutableArray *letterArray = [NSMutableArray array];
[self enumerateSubstringsInRange:NSMakeRange(0, [self length])
options:(option)
usingBlock:^(NSString *substring,
NSRange substringRange,
NSRange enclosingRange,
BOOL *stop) {
[letterArray addObject:substring];
}];
NSMutableArray *array = [NSMutableArray array];
[letterArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
if (idx%size == 0) {
[array addObject: [NSMutableString stringWithCapacity:size]];
}
NSMutableString *string = [array objectAtIndex:[array count]-1];
[string appendString:obj];
}];
return array;
}
#end
usage
NSArray *array = [#"E44000000R33000444V33441" arraysBySplittingWithMaximumSize:9
options:NSStringEnumerationByComposedCharacterSequences];
results in:
(
E44000000,
R33000444,
V33441
)
I'm trying to re-arrange words into alphabetical order. For example, tomato would become amoott, or stack would become ackst.
I've found some methods to do this in C with char arrays, but I'm having issues getting that to work within the confines of the NSString object.
Is there an easier way to do it within the NSString object itself?
You could store each of the string's characters into an NSArray of NSNumber objects and then sort that. Seems a bit expensive, so I would perhaps just use qsort() instead.
Here it's provided as an Objective-C category (untested):
NSString+SortExtension.h:
#import <Foundation/Foundation.h>
#interface NSString (SortExtension)
- (NSString *)sorted;
#end
NSString+SortExtension.m:
#import "NSString+SortExtension.h"
#implementation NSString (SortExtension)
- (NSString *)sorted
{
// init
NSUInteger length = [self length];
unichar *chars = (unichar *)malloc(sizeof(unichar) * length);
// extract
[self getCharacters:chars range:NSMakeRange(0, length)];
// sort (for western alphabets only)
qsort_b(chars, length, sizeof(unichar), ^(const void *l, const void *r) {
unichar left = *(unichar *)l;
unichar right = *(unichar *)r;
return (int)(left - right);
});
// recreate
NSString *sorted = [NSString stringWithCharacters:chars length:length];
// clean-up
free(chars);
return sorted;
}
#end
I think separate the string to an array of string(each string in the array contains only one char from the original string). Then sort the array will be OK. This is not efficient but is enough when the string is not very long. I've tested the code.
NSString *str = #"stack";
NSMutableArray *charArray = [NSMutableArray arrayWithCapacity:str.length];
for (int i=0; i<str.length; ++i) {
NSString *charStr = [str substringWithRange:NSMakeRange(i, 1)];
[charArray addObject:charStr];
}
NSString *sortedStr = [[charArray sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)] componentsJoinedByString:#""];
// --------- Function To Make an Array from String
NSArray *makeArrayFromString(NSString *my_string) {
NSMutableArray *array = [[NSMutableArray alloc] init];
for (int i = 0; i < my_string.length; i ++) {
[array addObject:[NSString stringWithFormat:#"%c", [my_string characterAtIndex:i]]];
}
return array;
}
// --------- Function To Sort Array
NSArray *sortArrayAlphabetically(NSArray *my_array) {
my_array= [my_array sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
return my_array;
}
// --------- Function Combine Array To Single String
NSString *combineArrayIntoString(NSArray *my_array) {
NSString * combinedString = [[my_array valueForKey:#"description"] componentsJoinedByString:#""];
return combinedString;
}
// Now you can call the functions as in below where string_to_arrange is your string
NSArray *blowUpArray;
blowUpArray = makeArrayFromString(string_to_arrange);
blowUpArray = sortArrayAlphabetically(blowUpArray);
NSString *arrayToString= combineArrayIntoString(blowUpArray);
NSLog(#"arranged string = %#",arrayToString);
Just another example using NSMutableString and sortUsingComparator:
NSMutableString *mutableString = [[NSMutableString alloc] initWithString:#"tomat"];
[mutableString appendString:#"o"];
NSLog(#"Orignal string: %#", mutableString);
NSMutableArray *charArray = [NSMutableArray array];
for (int i = 0; i < mutableString.length; ++i) {
[charArray addObject:[NSNumber numberWithChar:[mutableString characterAtIndex:i]]];
}
[charArray sortUsingComparator:^NSComparisonResult(id _Nonnull obj1, id _Nonnull obj2) {
if ([obj1 charValue] < [obj2 charValue]) return NSOrderedAscending;
return NSOrderedDescending;
}];
[mutableString setString:#""];
for (int i = 0; i < charArray.count; ++i) {
[mutableString appendFormat:#"%c", [charArray[i] charValue]];
}
NSLog(#"Sorted string: %#", mutableString);
Output:
Orignal string: tomato
Sorted string: amoott
I have a search string, where people can use quotes to group phrases together, and mix this with individual keywords. For example, a string like this:
"Something amazing" rooster
I'd like to separate that into an NSArray, so that it would have Something amazing (without quotes) as one element, and rooster as the other.
Neither componentsSeparatedByString nor componentsSeparatedByCharactersInSet seem to fit the bill. Is there an easy way to do this, or should I just code it up myself?
You probably will have to code some of this up yourself, but the NSScanner should be a good basis on which to build. If you use the scanUpToCharactersInSet method to look for everything up to your next whitespace or quote character to can pick off words. Once you encounter a quite character, you could continue to scan using just the quote in the character set to end at, so that spaces within the quotes don't result in the end of a token.
I made a simple way to do this using NSScanner:
+ (NSArray *)arrayFromTagString:(NSString *)string {
NSScanner *scanner = [NSScanner scannerWithString:string];
NSString *substring;
NSMutableArray *array = [[NSMutableArray alloc] init];
while (scanner.scanLocation < string.length) {
// test if the first character is a quote
unichar character = [string characterAtIndex:scanner.scanLocation];
if (character == '"') {
// skip the first quote and scan everything up to the next quote into a substring
[scanner setScanLocation:(scanner.scanLocation + 1)];
[scanner scanUpToString:#"\"" intoString:&substring];
[scanner setScanLocation:(scanner.scanLocation + 1)]; // skip the second quote too
}
else {
// scan everything up to the next space into the substring
[scanner scanUpToString:#" " intoString:&substring];
}
// add the substring to the array
[array addObject:substring];
//if not at the end, skip the space character before continuing the loop
if (scanner.scanLocation < string.length) [scanner setScanLocation:(scanner.scanLocation + 1)];
}
return array.copy;
}
This method will convert the array back to a tag string, re-quoting the multi-word tags:
+ (NSString *)tagStringFromArray:(NSArray *)array {
NSMutableString *string = [[NSMutableString alloc] init];
NSRange range;
for (NSString *substring in array) {
if (string.length > 0) {
[string appendString:#" "];
}
range = [substring rangeOfString:#" "];
if (range.location != NSNotFound) {
[string appendFormat:#"\"%#\"", substring];
}
else [string appendString:substring];
}
return string.description;
}
I ended up going with a regular expression as I was already using RegexKitLite, and creating this NSString+SearchExtensions category.
.h:
// NSString+SearchExtensions.h
#import <Foundation/Foundation.h>
#interface NSString (SearchExtensions)
-(NSArray *)searchParts;
#end
.m:
// NSString+SearchExtensions.m
#import "NSString+SearchExtensions.h"
#import "RegexKitLite.h"
#implementation NSString (SearchExtensions)
-(NSArray *)searchParts {
__block NSMutableArray *items = [[NSMutableArray alloc] initWithCapacity:5];
[self enumerateStringsMatchedByRegex:#"\\w+|\"[\\w\\s]*\"" usingBlock: ^(NSInteger captureCount,
NSString * const capturedStrings[captureCount],
const NSRange capturedRanges[captureCount],
volatile BOOL * const stop) {
NSString *result = [capturedStrings[0] stringByReplacingOccurrencesOfRegex:#"\"" withString:#""];
NSLog(#"Match: '%#'", result);
[items addObject:result];
}];
return [items autorelease];
}
#end
This returns an NSArray of strings with the search strings, removing the double quotes that surround the phrases.
If you'll allow a slightly different approach, you could try Dave DeLong's CHCSVParser. It is intended to parse CSV strings, but if you set the space character as the delimiter, I am pretty sure you will get the intended behavior.
Alternatively, you can peek into the code and see how it handles quoted fields - it is published under the MIT license.
I would run -componentsSeparatedByString:#"\"" first, then create a BOOL isPartOfQuote, initialized to YES if the first character of the string was a ", but otherwise set to NO.
Then create a mutable array to return:
NSMutableArray* masterArray = [[NSMutableArray alloc] init];
Then, create a loop over the array returned from the separation:
for(NSString* substring in firstSplitArray) {
NSArray* secondSplit;
if (isPartOfQuote == NO) {
secondSplit = [substring componentsSeparatedByString:#" "];
}
else {
secondSplit = [NSArray arrayWithObject: substring];
}
[masterArray addObjectsFromArray: secondSplit];
isPartOfQuote = !isPartOfQuote;
}
Then return masterArray from the function.