How to find string length Without use length algorithm. Please any one suggest me. What type of algorithm used to find string length.
Already i know [str length];
Any other option is available or not? If available means tell me.
Thanks.
I hope this helps you
NSString *foo = #"IDontWantToUseStringLength";
const wchar_t *str = (const wchar_t*)[foo cStringUsingEncoding:NSUTF16StringEncoding];
int len = 0;
while (str[len] != '\0') {
len++;
}
Related
Im struggling to covert chinese word/characters to ascii or hexadecimal and all the values I've got up until now is not what I was suppose to get.
Example of conversion is the word 手 to hex is 1534b.
Methods Ive followed till now are as below, and I got varieties of results but the one I was looking for,
I really appreciate if you can help me out on this issue,
Thanks,
Mike
- (NSString *) stringToHex:(NSString *)str{
NSUInteger len = [str length];
unichar *chars = malloc(len * sizeof(unichar));
[str getCharacters:chars];
NSMutableString *hexString = [[NSMutableString alloc] init];
for(NSUInteger i = 0; i < len; i++ )
{
[hexString appendFormat:#"%02x", chars[i]]; //EDITED PER COMMENT BELOW
}
free(chars);
return hexString;}
and
const char *cString = [#"手" cStringUsingEncoding:NSASCIIStringEncoding];
below is the similar code in Java for Android, Maybe it helps
public boolean sendText(INotifiableManager manager, String text) {
final int codeOffset = 0xf100;
for (char c : text.toCharArray()) {
int code = (int)c+codeOffset;
if (! mConnection.getBoolean(manager, "SendKey", Integer.toString(code))) {
}
Your Java code is just doing this:
Take each 16-bit character of the string and add 0xf100 to it.
If you do the same thing in your above Objective-C code you will get the result you want.
I have seen questions in stackoverflow that convert unichar to NSString but now I would like to do the reverse.
How do i do it?
Need some guidance.. Thanks
For example, I have an array of strings:[#"o",#"p",#"q"];
These are strings inside. How do i convert it back to unichar?
The following will work as long as the first character isn't actually two composed characters (in other words as long as the character doesn't have a Unicode value greater than \UFFFF):
unichar ch = [someString characterAtIndex:0];
You could convert it to a buffer in NSData:
if ([string canBeConvertedToEncoding:NSUnicodeStringEncoding]) {
NSData * data = [string dataUsingEncoding:NSUnicodeStringEncoding];
const unichar* const ptr = (const unichar*)data.bytes;
...
}
We need to convert the below datatypes to binary:
Long long to Binary
NSUInteger to Binary
Any help on this would be highly appreciated.
The code i have is :
As per the above link, we have
- (NSString *) longlongToBinary:(long long) val {
long long num = val;
NSString *res = [NSString string];
for (long long i=63; i>=0; i--)
{
long long div = 1l<<i;
if ((num&div)==div) res = [res stringByAppendingString:#"1"];
else res = [res stringByAppendingString:#"0"];
}
return res;
}
If the val is 20, then the output i am getting is:
0000000000000000000000000001010000000000000000000000000000010100
and this is wrong when i see it in the online convertors.
long is only 32 bits. Since the method is named longlongToBinary, change all of the long variables to long long. That will give you the 64 bits you are using.
Now that you have changed most variables to long long, change the loop variable i back to an int and change the 1l constant to 1ll.
The literal 1l is still only long. That's why you see the output twice. Change the literal to 1ll
I am trying to create an NSString object from a const unichar buffer where I don't know the length of the buffer.
I want to use the NSString stringWithCharacters: length: method to create the string (this seems to work), but please can you help me find out the length?
I have:
const unichar *c_emAdd = [... returns successfully from a C++ function...]
NSString *emAdd = [NSString stringWithCharacters:c_emAdd length = unicharLen];
Can anyone help me find out how to check what unicharLen is? I don't get this length passed back to me by the call to the C++ function, so I presume I'd need to iterate until I find a terminating character? Anyone have a code snippet to help? Thanks!
Is your char buffer null terminated?
Is it 16-bit unicode?
NSString *emAdd = [NSString stringWithFormat:#"%S", c_emAdd];
Your unichars should be null terminated so you when you reach two null bytes (a unichar = 0x0000) in the pointer you will know the length.
unsigned long long unistrlen(unichar *chars)
{
unsigned long long length = 0llu;
if(NULL == chars) return length;
while(NULL != chars[length])
length++;
return length;
}
//...
//Inside Some method or function
unichar chars[] = { 0x005A, 0x0065, 0x0062, 0x0072, 0x0061, 0x0000 };
NSString *string = [NSString stringWithCharacters:chars length:unistrlen(chars)];
NSLog(#"%#", string);
Or even simpler format with %S specifier
I have a binary file I've loaded using an NSData object. Is there a way to locate a sequence of characters, 'abcd' for example, within that binary data and return the offset without converting the entire file to a string? Seems like it should be a simple answer, but I'm not sure how to do it. Any ideas?
I'm doing this on iOS 3 so I don't have -rangeOfData:options:range: available.
I'm going to award this one to Sixteen Otto for suggesting strstr. I went and found the source code for the C function strstr and rewrote it to work on a fixed length Byte array--which incidentally is different from a char array as it is not null terminated. Here is the code I ended up with:
- (Byte*)offsetOfBytes:(Byte*)bytes inBuffer:(const Byte*)buffer ofLength:(int)len;
{
Byte *cp = bytes;
Byte *s1, *s2;
if ( !*buffer )
return bytes;
int i = 0;
for (i=0; i < len; ++i)
{
s1 = cp;
s2 = (Byte*)buffer;
while ( *s1 && *s2 && !(*s1-*s2) )
s1++, s2++;
if (!*s2)
return cp;
cp++;
}
return NULL;
}
This returns a pointer to the first occurrence of bytes, the thing I'm looking for, in buffer, the byte array that should contain bytes.
I call it like this:
// data is the NSData object
const Byte *bytes = [data bytes];
Byte* index = [self offsetOfBytes:tag inBuffer:bytes ofLength:[data length]];
Convert your substring to an NSData object, and search for those bytes in the larger NSData using rangeOfData:options:range:. Make sure that the string encodings match!
On iPhone, where that isn't available, you may have to do this yourself. The C function strstr() will give you a pointer to the first occurrence of a pattern within the buffer (as long as neither contain nulls!), but not the index. Here's a function that should do the job (but no promises, since I haven't tried actually running it...):
- (NSUInteger)indexOfData:(NSData*)needle inData:(NSData*)haystack
{
const void* needleBytes = [needle bytes];
const void* haystackBytes = [haystack bytes];
// walk the length of the buffer, looking for a byte that matches the start
// of the pattern; we can skip (|needle|-1) bytes at the end, since we can't
// have a match that's shorter than needle itself
for (NSUInteger i=0; i < [haystack length]-[needle length]+1; i++)
{
// walk needle's bytes while they still match the bytes of haystack
// starting at i; if we walk off the end of needle, we found a match
NSUInteger j=0;
while (j < [needle length] && needleBytes[j] == haystackBytes[i+j])
{
j++;
}
if (j == [needle length])
{
return i;
}
}
return NSNotFound;
}
This runs in something like O(nm), where n is the buffer length, and m is the size of the substring. It's written to work with NSData for two reasons: 1) that's what you seem to have in hand, and 2) those objects already encapsulate both the actual bytes, and the length of the buffer.
If you're using Snow Leopard, a convenient way is the new -rangeOfData:options:range: method in NSData that returns the range of the first occurrence of a piece of data. Otherwise, you can access the NSData's contents yourself using its -bytes method to perform your own search.
I had the same problem.
I solved it doing the other way round, compared to the suggestions.
first, I reformat the data (assume your NSData is stored in var rawFile) with:
NSString *ascii = [[NSString alloc] initWithData:rawFile encoding:NSAsciiStringEncoding];
Now, you can easily do string searches like 'abcd' or whatever you want using the NSScanner class and passing the ascii string to the scanner. Maybe this is not really efficient, but it works until the -rangeOfData method will be available for iPhone also.