Hiya.
I have a char array where I want to check bytes 5-16 against a given string, for the purpose of identifying a product I'm communicating with.
If the amount of characters were smaller, I'd just use an "if byte[n] == 0x??" check. But with 11 bytes, this seems a bit brutal. Is there a more elegant way to do this?
Thanks!
How about:
if (strncmp(&to_test[5], "is it this", 10) == 0) {
where 10 is the length of "it it this"
Is there a more elegant way to do this?
Essentially the "savings" is having the pre-written routine do the byte-by-byte comparison for you.
For any spot in the string, start with strstr(). If you have more position information then strncmp()or memcmp().
Lee
Cliff, Cliff.. What would you say if someone you're bossing around at work all day produced that code? :wink:
I'd expect at least this:
#define THE_NAME "is it this"
.
.
.
if (strncmp(&to_test[5], THE_NAME, strlen(THE_NAME)) == 0) {
And then awew get into the discussion about tossing that string (those strings?) into PROGMEM..
Johan,
Yup I knew that as I typed it but I was trying to keep it as simple as possible to show the "raw" use of strncmp and not overload/complicate it with the obvious use for strlen() (at least I hoped it WOULD be obvious!)
Cliff
at least I hoped it WOULD be obvious!
Strncmp will stop at any null character (or maybe not?) in any of the strings, and "is it this" will be null-terminated regardless of how we play around with it. And it is 10 characters, not 12 as is the case with positions 5-16. Is there a null terminator anywhere in those positions? Why is OP saying that pos 5-16 is 11 characters rather than 12? Why did I decide to spend my life in the s/w bussiness, and not as an anthropologist on a coral island?
Cliff, Cliff.. What would you say if someone you're bossing around at work all day produced that code? :wink:I'd expect at least this:
#define THE_NAME "is it this" . . . if (strncmp(&to_test[5], THE_NAME, strlen(THE_NAME)) == 0) {And then awew get into the discussion about tossing that string (those strings?) into PROGMEM..
if(strcmp(&to_test[5], THE_NAME))==0) {
is better.
It does the same job whether to_test has good data or not.
THE_NAME provides the bound.
strcmp_P might be better.
In BASIC:
For I = 5 to 16
If Chr(Array(I)) <> Mid(CompareString, I - 4, 1) Then
ComparePassed = False
End If
Next I
If ComparePassed = True
...
In BASIC
Haha well I can manage Python (which is very close to BASIC anyways), tcl, and moderate C. Just never took the time to properly learn C on embedded platforms... ;)
I'll edit this post not to clutter this thread more:
Python is pretty close to BASIC in syntax... Closer to BASIC than to C anyways. ;)
age = input("Enter your age (in human years): ")
print
if age < 0:
print "Negative age?!? I don't think so."
elif age < 3 or age > 110:
print "Frankly, I don't believe you."
else:
print "That's", age*7, "in dog years."
Same thing in BASIC:
Input "Enter your age (in human years): ", Age Print If Age < 0 Then print "Negative age?!? I don't think so." Elseif Age < 3 or Age > 110 Then print "Frankly, I don't believe you." Else print "That's", age*7, "in dog years." End If
Python (which is very close to BASIC anyways)
Thanks for the help. I landed on using a combination of the strncmpf() and strlenf() functions, since I had some issued with SRAM vs FLASH.
I've never been too good on memory handling.. :oops: :D