strncpy strange results

Projects Programming
1

Hi there

I have the following code within my program -

char code[10]; 
char codesent[10];

//code below is located in main loop
      Serial.println(code);
      strncpy (codesent,code);        //Take of copy of the code used for the transaction

I am have a code value in the variable "code" and sometimes I want to take a copy of it into "codesent" so I know what code has been sent out to the PC as the code value will constantly change. Using the following line "strncpy(codesent,code)" gives some very strange results. I would have thought that it should copy code into codesent.

Can anyone confirm if the above should work?

David

2

With strncpy() you have to specify how many characters to copy.

strncpy (codesent,code,10);
3

Note, also, that strncpy() doesn't insert the terminating null character.

4

From the docs;

"Copy a string.

The strncpy() function is similar to strcpy(), except that not more than n bytes of src are copied. Thus, if there is no null byte among the first n bytes of src, the result will not be null-terminated.

In the case where the length of src is less than that of n, the remainder of dest will be padded with nulls."