I'm trying to get each individual character of a string, gameWord, into an NSMutableArray.
I'm converting each char into an object and then adding the objects into the NSMutableArray with the following code:
NSMutableString *letterOne = [[NSMutableString alloc] initWithFormat:#"%C",[gameWord characterAtIndex:0]];
NSMutableString *letterTwo = [[NSMutableString alloc] initWithFormat:#"%C",[gameWord characterAtIndex:1]];
and so on....
What I don't understand is why the following loop won't work?
NSMutableArray *lettersArray = [[NSMutableArray alloc] initWithCapacity:[gameWord length]];
for (int x = 0 ; x <= [gameWord length] ; x++) {
NSMutableString *letter = [[NSMutableString alloc]initWithFormat:#"%C",[gameWord characterAtIndex:x]];
[lettersArray addObject:letter];
[letter release];
}
Would really appreciate help understanding this problem and any other ways of getting each character of an NSString into individual objects (not chars).
Your for loop goes beyond the length of the string. Arrays are zero-based, so the last object has the index [gameWord length] - 1.
This should work:
for (int x = 0; x < [gameWord length]; x++) {
//... ^--changed from <= to <
}
Related
I have an NSString *titleName which changes according to an if statement. So the length (number of characters) in the string changes. I would like to divide titleName into a MutableArray of separate strings consisting of its individual characters. I would then like to use these separate strings as the text in different UILabels. I am not sure as how to go about this.
Through some research I have tried to create the NSMutable array like this
NSMutableArray *letterArray = substringWithRange:((i = 0);i<[titleName2 length];i++));
but this gives me an error Use of undeclared identifier 'substringWithRange.
Can someone help me.
I decided to use componentsSeparatedByString instead and just created my various strings with a , between each letter. Thanks for anybody's thoughts though.
The code you pasted is not valid objective-C.
To keep the same algorithm you should write something like :
NSMutableArray *letterArray = [NSMutableArray array];
NSUInteger length = [titleName2 length];
for (NSUInteger i = 0; i < length; ++i) {
[letterArray addObject:[titleName2 substringWithRange:NSMakeRange(i, 1)]];
}
It's probably much "cheaper" to hold a C-array of unichar characters that make-up the string. It will also be quicker to create:
NSString *input = #"How now brown cow?";
unichar chars[[input length]];
for (NSInteger i = 0; i < [input length]; i++)
chars[i] = [input characterAtIndex:i];
Alternatively you could use malloc() to create the C-array:
NSString *input = #"How now brown cow?";
unichar *chars = (unichar *)malloc([input length]);
for (NSInteger i = 0; i < [input length]; i++)
chars[i] = [input characterAtIndex:i];
and then use free(), later, to, err, free the memory:
free(chars);
Cheaper still, would be to not split-up the string at all...
Try this below code
NSMutableArray *letterArray = [NSMutableArray array];
for (int i = 0;i<[titleName2 length];i++)
{
[letterArray addObject: [titleName2 substringWithRange:NSMakeRange(i,1)]];
}
DLog(#"%#", letterArray);
Other option to get characters of string
NSMutableArray *letterArray = [NSMutableArray array];
for (int i=0; i < [titleName2 length]; i++)
{
[letterArray addObject:[NSString stringWithFormat:#"%c", [titleName2 characterAtIndex:i]]];
}
DLog(#"characters - %#", letterArray);
What I am trying to achieve, is to convert a csv file into an array of custom objects, however, my attempts at this seem to result in all of the objects in the array being returned as the same object (the last object in the array).
Before I explain further, here is the code:
- (NSArray *)arrayFromCSVFileName:(NSString *)csvFileName fileType:(NSString *)fileType {
// Convert the file into an NSData object
NSString *studentFilePath = [[NSBundle mainBundle] pathForResource:csvFileName ofType:fileType];
NSData *studentData = [NSData dataWithContentsOfFile:studentFilePath];
// Convert the NSData into an NSString
NSString *csvString = [[NSString alloc] initWithData:studentData encoding:NSUTF8StringEncoding];
// Split each record (line) in the csvDataString into an individual array element (split on the newline character \n)
NSArray *csvArray = [csvString componentsSeparatedByString:#"\n"];
// Create an array to hold the parsed CSV data
NSMutableArray *parsedCSVArray = [[NSMutableArray alloc] init];
NSMutableArray *elementArray = [[NSMutableArray alloc] init];
CGSElement *elementToAdd = [[CGSElement alloc] init];
// Loop through each line of the file
for (int i = 0; i < [csvArray count]; i++) {
// Get a reference to this record (line) as a string, and remove any extranous new lines or alike
NSString *csvRecordString = [[csvArray objectAtIndex:i] stringByReplacingOccurrencesOfString:#"\r" withString:#""];
// Split the line by the comma delimeter
NSArray *csvRecordArray = [csvRecordString componentsSeparatedByString:#","];
// Check that there are actually fields (i.e. this is not a blank line)
if ( ([csvRecordArray count] > 0) && ([[csvRecordArray objectAtIndex:0] length] > 0) ) {
elementToAdd.mass = [[csvRecordArray objectAtIndex:1] floatValue];
elementToAdd.atomicNumber = [[csvRecordArray objectAtIndex:0] intValue];
elementToAdd.name = [csvRecordArray objectAtIndex:2];
elementToAdd.symbol = [csvRecordArray objectAtIndex:3];
elementToAdd.period = [[csvRecordArray objectAtIndex:4] intValue];
[elementArray addObject:elementToAdd];
}
}
for (int i = 0; i < [elementArray count]; i++) {
NSLog(#"%i", i);
CGSElement *current = [elementArray objectAtIndex:i];
NSLog(#"Name = %#", current.name);
}
// Return the parsed array
return elementArray;
}
The custom object in question is the CGSElement object, which I am attempting to fill the elementArray with. However, my debug code (the following section of code):
for (int i = 0; i < [elementArray count]; i++) {
NSLog(#"%i", i);
CGSElement *current = [elementArray objectAtIndex:i];
NSLog(#"Name = %#", current.name);
}
Is resulting, rather than in the return of all of the correct element names, it is returning the last element (to put this in context, ununoctium), 118 times.
After some testing, I can safely say that up until after this point:
elementToAdd.mass = [[csvRecordArray objectAtIndex:1] floatValue];
elementToAdd.atomicNumber = [[csvRecordArray objectAtIndex:0] intValue];
elementToAdd.name = [csvRecordArray objectAtIndex:2];
elementToAdd.symbol = [csvRecordArray objectAtIndex:3];
elementToAdd.period = [[csvRecordArray objectAtIndex:4] intValue];
All of the elements are being correctly defined, rather than just the same element over and over.
Needless to say, I'm stumped as to why it would be returning the same object over and over. Any help would be appreciated.
This line:
CGSElement *elementToAdd = [[CGSElement alloc] init];
Should be inside your loop, just before you try to edit the object and add it to the array. Currently you are repeatedly mutating the same object instead of creating new objects for each record.
You add the same entity all the time. It is crated once before the loop and within the loop it values are changed again and angan and it is added to the array. Naturally all items in the aray carry the same values because it is the same object.
If you want then change the array with an NSSet. To a set an object can only added once and you will end up with a set of 1. That is not the solution of couse, it would just visualize what is happening.
To solve it move this line
CGSElement *elementToAdd = [[CGSElement alloc] init];
to the beginning of the body of the for i loop, so that a new instance is created for every iteration and therefore for every index of the array.
If I have this:
int toSplit = 208;
What's the best way to split it so I get:
2
0
8
Method would be like this
- (NSMutableArray *) toCharArray : (NSString *) str
{
NSMutableArray *characters = [[NSMutableArray alloc] initWithCapacity:[str length]];
for (int i=0; i < [str length]; i++)
{
NSString *ichar = [NSString stringWithFormat:#"%c", [str characterAtIndex:i]];
[characters addObject:ichar];
}
return characters;
}
do {
int digit = toSplit % 10;
toSplit /= 10;
printf(#"%i", digit);
} while (toSplit > 0);
I hope it's not a homework.
EDIT: it's backwards so it's not a valid answer... However, leaving it here because it can still be useful for others.
Sort it into a string then pull it apart. So like this:
int toSplit = 208;
NSString *string = [NSString stringWithFormat: #"%i", toSplit];
NSMutableString *splitApartString = [[NSMutableString alloc] init];
for (int i = 0; i < [string length]; i++) {
NSString *substring = [string substringFromIndex: i];
[splitApartString appendFormat: #"%#\n", substring];
}
NSLog(#"%#", splitApartString); //YAY!
So what this does, is puts this int into a string, splits it apart, then iterates through each character and gets a string out of that character. Then it appends that substring to a NEW string.
Another alternative, is instead of getting a substring just get the char and use the %c operator. Also if you take a look at this code you will see this output:
> 2
> 0
> 8
> // extra space here
You could just add a condition to check if i is the string length - 1 and not add a space or you could just remove the last character!
I'm not familiar with Objective-C syntax, but something like:
void split(int toSplit)
{
if (!toSplit)
{
return;
}
split(toSplit / 10);
int digit = toSplit % 10;
printf(#"%i", digit);
}
There are many threads about going the opposite way, but I am interested in converting from a primitive C array to a NSArray. The reason for this is that I want to create a NSString from the array contents. To create the NSString I will use:
NSArray *array;
NSString *stringFromArray = [array componentsJoinedByString:#","];
I am joining the elements of the array by commas because I will later be saving the string as a .csv file. I don't think it matters, but the C array I am dealing with is of type double and size 43.
double c_array = new double [43];
Thanks!
NSString * stringFromArray = NULL;
NSMutableArray * array = [[NSMutableArray alloc] initWithCapacity: 43];
if(array)
{
NSInteger count = 0;
while( count++ < 43 )
{
[array addObject: [NSString stringWithFormat: #"%f", c_array[count]]];
}
stringFromArray = [array componentsJoinedByString:#","];
[array release];
}
I'm having a rather annoying problem here. See, I'm trying to break up a string that I get into individual characters and symbols. The string is always in the form of an equation, like "3x+4" or "x/7+5". I need to separate the string into an array of individual strings. For example, if I had the first equation, I would want to have an NSMutableArray that has "3", "x", "+", and "4". Here is the section of code that I use:
NSMutableArray* list = [[NSMutableArray alloc] initWithCapacity:10];
for (int i = 0; i < [self.equationToGuess length]; i++) {
NSRange range = {i, i};
NSString* string= [[NSString alloc] initWithString:[self.equationToGuess substringWithRange:range]];
[list addObject:string];
}
I've made sure to check if self.equationToGuess always contains an equation using the debugger, and it does. list is also able to get some of the objects, but the problem is that it just puts the last two characters in one shelf on the list. So if I have that "3x+4" equation, this chunk of code puts "3", "x", and "+4" into the code, and then it crashes because it goes beyond the length of the string. Does anyone know how to fix this?
The two values in NSRange are not the starting and ending index. Rather, the first is the starting index and the second is the length of the range. So instead you want your range to be
NSRange range = NSMakeRange(i, 1);
Let's do this with a bit more panache:
NSInteger numberOfCharacters = [self.equationToGuess length];
NSMutableArray *characterArray = [[NSMutableArray alloc] initWithCapacity:numberOfCharacters];
for (NSUInteger idx = 0; idx < numberOfCharacters; idx++) {
NSRange range = NSMakeRange(idx, 1);
[characterArray addObject:[self.equationToGuess substringWithRange:range]];
}
Edit
After a hearty helping of humble pie - this is still not the best way to do it: if your equation has multi-digit coefficients, they will be split up. Have you considered using NSScanner to split the string up instead?
you could also use an alternative solution by getting characters from you string , for that you will have to use the below function of NSString.
- (unichar)characterAtIndex:(NSUInteger)index
.
NSMutableArray* list = [[NSMutableArray alloc] initWithCapacity:10];
NSString* string;
for (int i = 0; i < [self.equationToGuess length]; i++)
{
string = [[NSString alloc] initWithFormat:#"%c",[self.equationToGuess characterAtIndex:i]];
[list addObject:string];
[string release];
string = nil ;
}
NSInteger numberOfCharacters = [self.equationToGuess length];
NSMutableArray *characterArray = [[NSMutableArray alloc] initWithCapacity:numberOfCharacters];
for (NSUInteger idx = 0; idx < numberOfCharacters; idx++) {
[characterArray addObject:[NSString stringWithFormat:#"%c", [self.equationToGuess characterAtIndex:idx]]];
}