I have a C function that looks like: 
 
int myfunction(char* error_string)

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This function returns an error description in error_string if there is an error. I want to call this function from my Perl code but I'm not sure how to get the string back correctly. The following test code seems to work (sort of): 

my $error = "          ";
mylib::myfunction($error);
print $error;

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This works as long as the string being returned is shorter than the number of spaces in the initialization of $error (10 spaces in this case), however any additional spaces in $error will still be printed after the error. For example, if the error returned is "Error 1", "Error 1   " will be printed with 3 spaces at the end. If the error returned is longer than 10 characters, the additional characters are truncated. I'm assuming this is becuase Perl counts the characters in a string instead of using null termination. Is there any way I can get Perl to "recount" the length of the string after returning from the function? I suppose I could search for the end of the string but it seems like there should be a better way to do this. Also, is there a better way to define the string I want to pass in to the function? The actual string needs to be 400 characters long and I'm not sure how to specify that I want a string with 400 characters. I suppose I could use a loop or the x operator to fill the string with spaces or some other character, but is there a better way to just allocate space for 400 characters?

In reply to Passing a string from C to Perl by Anonymous Monk

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