How can I compare each character of CCString with each character of other CCString in cocos2dx ?
Thank you
Cocos2dx is based on CPP right? Just get the string to char array and then use ordinary string comparison functions such as strcmp..
I treat your "compare each character" as "compare equal".
For example:
CCString *pStrA, *pStrB;
string strA = pStrA->toStdString();
string strB = pStrB->toStdString();
if (strA == strB) {
// do something
}
There is the method in CCString to compare the string
EXample
string1->compare(string2->getCString()); (or whatever the correctly named functions are)
that function returns a number, which i think is the difference between the first letter that is wrong, eg a-b = -1 or b-d = 2.. I think this is for sorting things alphabetically... someone correct me if not?
basically if you get 0 from it, then the string is the same all the way through. so:
CCString *string1 = CCString::create("Hi");
CCString *string2 = CCString::create("Hi");
if(string1->compare(string2->getCString()) == 0){
//they are the same
}else{
//different
}
Related
I have a character array and I'm trying to figure out if it matches a string literal, for example:
char value[] = "yes";
if(value == "yes") {
// code block
} else {
// code block
}
This resulted in the following error: comparison with string literal results in unspecified behavior. I also tried something like:
char value[] = "yes";
if(strcmp(value, "yes")) {
// code block
} else {
// code block
}
This didn't yield any compiler errors but it is not behaving as expected.
Check the documentation for strcmp. Hint: it doesn't return a boolean value.
ETA: == doesn't work in general because cstr1 == cstr2 compares pointers, so that comparison will only be true if cstr1 and cstr2 point to the same memory location, even if they happen to both refer to strings that are lexicographically equal. What you tried (comparing a cstring to a literal, e.g. cstr == "yes") especially won't work, because the standard doesn't require it to. In a reasonable implementation I doubt it would explode, but cstr == "yes" is unlikely to ever succeed, because cstr is unlikely to refer to the address that the string constant "yes" lives in.
std::strcmp returns 0 if strings are equal.
strcmp returns a tri-state value to indicate what the relative order of the two strings are. When making a call like strcmp(a, b), the function returns
a value < 0 when a < b
0 when a == b
a value > 0 when a > b
As the question is tagged with c++, in addition to David Seilers excellent explanation on why strcmp() did not work in your case, I want to point out, that strcmp() does not work on character arrays in general, only on null-terminated character arrays (Source).
In your case, you are assigning a string literal to a character array, which will result in a null-terminated character array automatically, so no problem here. But, if you slice your character array out of e. g. a buffer, it may not be null-terminated. In such cases, it is dangerous to use strcmp() as it will traverse the memory until it finds a null byte ('\0') to form a string.
Another solution to your problem would be (using C++ std::string):
char value[] = "yes";
if (std::string{value} == "yes")) {
// code block
} else {
// code block
}
This will also only work for null-terminated character arrays. If your character array is not null-terminated, tell the std::string constructor how long your character array is:
char value[3] = "yes";
if (std::string{value, 3} == "yes")) {
// code block
} else {
// code block
}
Can someone help me to understand how i need to send the parameters to the function "lora_rf_config" ? Thank you so much !
I try with:
char cfgred[7][10]={'lora_rf_config','915000000','10','0','1','8','14'};
lora_rf_config(7,&cfgred);
The function that im trying to use is:
static void lora_rf_config(int argc, char *argv[])
{
if (argc == 1) {
e_printf("OK%d,%d,%d,%d,%d,%d\r\n", g_lora_config.lorap2p_param.Frequency,
g_lora_config.lorap2p_param.Spreadfact,
g_lora_config.lorap2p_param.Bandwidth,
g_lora_config.lorap2p_param.Codingrate,
g_lora_config.lorap2p_param.Preamlen,
g_lora_config.lorap2p_param.Powerdbm );
return;
} else {
if (argc != 7) {
out_error(RAK_ARG_ERR);
return;
}
if (!(CHECK_P2P_FREQ(atoi(argv[1])) &&
CHECK_P2P_SF(atoi(argv[2])) &&
CHECK_P2P_BDW(atoi(argv[3])) &&
CHECK_P2P_CR(atoi(argv[4])) &&
CHECK_P2P_PREMLEN(atoi(argv[5])) &&
CHECK_P2P_PWR(atoi(argv[6])))) {
out_error(RAK_ARG_ERR);
return;
}
if (read_partition(PARTITION_0, (char *)&g_lora_config, sizeof(g_lora_config)) < 0) {
out_error(RAK_RD_CFG_ERR);
return;
}
g_lora_config.lorap2p_param.Frequency = atoi(argv[1]);
g_lora_config.lorap2p_param.Spreadfact = atoi(argv[2]);
g_lora_config.lorap2p_param.Bandwidth = atoi(argv[3]);
g_lora_config.lorap2p_param.Codingrate = atoi(argv[4]);
g_lora_config.lorap2p_param.Preamlen = atoi(argv[5]);
g_lora_config.lorap2p_param.Powerdbm = atoi(argv[6]);
write_partition(PARTITION_0, (char *)&g_lora_config, sizeof(g_lora_config));
e_printf("OK\r\n");
}
return;
}
The error that i got is:
..\..\..\src\application\RAK811\app.c(107): error: #26: too many characters in character constant
char cfgred[7][10]={'lora_rf_config','915000000','10','0','1','8','14'};
I dont have experience with this kind of arguments.
Thank you for your time.
lora_rf_config expects same arguments than main function: array of pointers to strings, and its length.
Strings in C are pointers to char, where the char buffer they point to has terminating NUL character (if NUL char is missing, then it's not a string, just a character array). In other words, there is no string type in C, but stringiness is determined by the actual data in the char array or buffer. Using "" string literal creates a string, IOW it adds that terminating NUL char in addition to what you write.
// cfgred is array([) of 7 pointers(*) to char.
// Note: string literals are read-only, so you must not modify these
// strings. If you want a modifiable string, this would be a bit more complex,
// but I think this is out of the scope of your question.
char *cfgred[7] = { "lora_rf_config" , "915000000", "10","0", "1", "8", "14"};
// you can get the number of elements in array by dividing its sizeof size (bytes)
// with the size of it's elements in bytes. Just make sure cfgred here is array...
// in the function it is pointer already (arrays get converted to pointers, so
// you can't do this inside the function, you have to do it where you still have
// the original array
int cfgred_len = sizeof cfgred / sizeof(cfgred[0]);
// when you pass array to function, it is automatically converted to pointer,
// so you must not use & when passing an array like this, otherwise types don't
// match
lora_rf_config(cfgred_len, cfgred);
As a side note, always turn on compiler warnings... They help you a lot, fix them. For gcc and clagn, use -Wall -Wextra, for Visual Studio use /W3 or prefereably /W4. And then fix any warnings you get, because they are probably something that doesn't do what you expect.
Your initialization is not done correctly, try changing
char cfgred[7][10]={'lora_rf_config','915000000','10','0','1','8','14'};
into
char cfgred[7][16]={"lora_rf_config","915000000","10","0","1","8","14"};
What is the regular expression (in JavaScript if it matters) to only match if the text is an exact match? That is, there should be no extra characters at other end of the string.
For example, if I'm trying to match for abc, then 1abc1, 1abc, and abc1 would not match.
Use the start and end delimiters: ^abc$
It depends. You could
string.match(/^abc$/)
But that would not match the following string: 'the first 3 letters of the alphabet are abc. not abc123'
I think you would want to use \b (word boundaries):
var str = 'the first 3 letters of the alphabet are abc. not abc123';
var pat = /\b(abc)\b/g;
console.log(str.match(pat));
Live example: http://jsfiddle.net/uu5VJ/
If the former solution works for you, I would advise against using it.
That means you may have something like the following:
var strs = ['abc', 'abc1', 'abc2']
for (var i = 0; i < strs.length; i++) {
if (strs[i] == 'abc') {
//do something
}
else {
//do something else
}
}
While you could use
if (str[i].match(/^abc$/g)) {
//do something
}
It would be considerably more resource-intensive. For me, a general rule of thumb is for a simple string comparison use a conditional expression, for a more dynamic pattern use a regular expression.
More on JavaScript regexes: https://developer.mozilla.org/en/JavaScript/Guide/Regular_Expressions
"^" For the begining of the line "$" for the end of it. Eg.:
var re = /^abc$/;
Would match "abc" but not "1abc" or "abc1". You can learn more at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
This may be a stupid question but I might aswell as it :)
is there away to force
$tel1 = '05';// string
settype($tel1,'string');
$tel1 = 06;//either throw error, or convert it to string automatically.
var_dump($tel1);//(string [2]) 05
The above code is of the top of my head so might not be accurate but I need to keep a variable as a string not numeric, because of some silly thing I have done, now my phone numbers lose the leading 0s :-(
n I cn't rewrite it because it will mess up with other numeric types,b4 u ask it was an automated service for db to check if it was a numeric value or not,
UPDATE
This is the problem
function escape($str){
if(is_numeric($str)){
return $str;
}else{
return "'".mysql_real_escape_string($str).'\'';
}
}
$tel1 = "06";
$sql = 'SELECT * FROM blabla WHERE id = '.escape($tel1).'';
//above is same as below
$sql = 'SELECT * FROM blabla WHERE id = 06 ';
I can't change anything inside the scape function because other inputes thruout the website are using this function, I dont wanna mess their validations.
Your use of is_numeric tests for numeric content, not an integer type. But then you take a variable called $str which implies you want it to be a string.
Perhaps use:
function escape($val) {
if (is_numeric($val) && !is_string($val)) {
return $val;
}
else{
return "'" . mysql_real_escape_string($val) . '\'';
}
}
Now strings will be escaped and quoted, but not if they contain only numeric content.
you can do something like:
$string = (string) $int;
or use a function
$string = strval($int);
You can't force a variable to a specific type in the global scope.
You can force Arrays and Objects in a function.
function getElementsByClassName(DOMNode $parentElement, Array $classNames) {
...
}
If you pass an object that is not an instantiation of DOMNode (or a subclass), or if you don't pass an Array as the second argument, you'll get an error.
You can of course cast any variable, e.g. (string) $tel1.
You shouldn't be treating phone numbers as Ints anyway, because of leading zeroes and possible parenthesis and dashes. Also, once your telephone number is an Int, it won't know its 0 padding anymore because it will be discarded, so casting it back won't give you the original String.
To cast a variable you can use something like:
$i = 1;
$s = (string) $i;
Depending on the db adaptor you might not be able to detect the type being returned from the database. I believe it's PDO that returns everything (even INT values) as strings.
The number_format() function may be of use to you too.
If you declare a variable as:
$var = 06;
it immediately becomes 6 without leading zero because leading zero when it comes to integers is meaningless and therefore it's cut out.
In other words, your variable has to be created as string, which is what you probably deduced yourself.
Quick fix would be the following: you can add another parameter to your escape() function.
For example:
function escape($str, $force_str = false)
{
if($force_str)
{
// do your conversion, the rest of the site will by default pass false so nothing will be broken
}
}
As alex said, start by making sure the phone number is never converted from string to int in your own code. Then, you need to make sure it will not be converted when sent to your SQL DB.
It ought to work if you do it this way:
$sql = "SELECT * FROM blabla WHERE id = '" . mysql_real_escape_string($tel1) . "'";
This is the same as
$sql = "SELECT * FROM blabla WHERE id = '06'";
Is there a way to test a string, such as the one below to see if it's an actual number value?
var theStr:String = '05';
I want to differentiate between the string value above and one such as this:
var theStr2:String = 'asdfl';
Thanks!
Yes use isNaN function to test if it the String is a valid Number:
var n:Number=Number(theStr);
if (isNaN(n)){
trace("not a number");
} else {
trace("number="+n);
}
You must cast to Number to get is NaN. If you use int letters can be cast to 0.
If you are just interested in checking integers you could use the match function as follows, the regex for numbers is more complicated and you would likely be better off following the casting method Patrick provided.
if (s.match(/^\d+$/)){//do something}
Of course if you are going to need to cast it anyway then using isNaN makes perfect sense. Just thought I'd offer an alternative in case you weren't going to cast it.
This code will return true if s contains only digits (no spaces, decimals, letters etc...) and requires there be at least 1 digit.