character array handling in c (copy pointer to character array)

Question

I have a pointer with type const char* FunctionName , How can I put that into a payload of type char payload[100] without any warning or errors? Also the payload[0] is filled with character value already, so the space starting from payload[1]

update:

I tried like this `strcpy((&payload[1]),FunctionName); is working now.

But Ihave one more question, how can accomodate the pointer(FunctionName) into the payload[1] ratherthan copying the entire string? through any assignment statement?

/R

what do you have so far?

AndersK
– AndersK

2011-09-28 09:06:57 +00:00
Commented Sep 28, 2011 at 9:06 — AndersK
– AndersK, Commented Sep 28, 2011 at 9:06

Vicky · Accepted Answer · 2011-09-28 09:01:35Z

3

strncpy(&payload[1], FunctionName, 98);
payload[99] = '\0';

should be safe in the case that FunctionName has more than 98 characters before the NULL terminator.

answered Sep 28, 2011 at 9:01

Vicky

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12 Comments

Sandip Agarwal Over a year ago

what happens if FunctionName has less than 98 characters? I mean to say where should the NULL terminator be placed?

Vicky Over a year ago

strncpy will pad the buffer with NULLs up to 98 if FunctionName is shorter than that, so you don't need to do anything different.

Sandip Agarwal Over a year ago

Great. It worked.. Don't you think, if the padding is done automatically, then the payload[99] = '\0'; statement isn't required?

Vicky Over a year ago

No, the last line is required if the FunctionName has >= 98 characters. Rather than performing an expensive strlen() on FunctionName first, just append the NULL. It's true it's not needed if FunctionName is always less than 98 characters but this is just good defensive coding practice. If you leave it out, someone will inevitably come along and call your code with a FunctionName longer than you were expecting some time in the future.

Vicky Over a year ago

@Renjith G: you need to use &payload[1] (the address of element 1 of payload) as the first argument - you are using the content of element 1 of payload with your statement. But strcpy (rather than strncpy) is not safe as I have explained.

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