In the following code, the minimum size for cOut is 25 as seen. However, the length of cOut by the time this code is run is 17, which would make me think that the minimum size for cOut should be 18. Anything lower than 25 causes a segmentation fault. Does the function strcat need some extra elements in the string for intermediate operations or something?

char *cTemp, cOut[25] = "rho_of_t_", cRight[5];

iRight = "1512"

// convert integer to string
sprintf(cRight, "%d", iRight);
// concatenate strings
strcat(cOut, cRight);
strcat(cOut, ".dat");



Thanks!

char * cOut[25] is an array-of-ptrs-to char (25 to be exact)
char cOut[25] is an array-of-char (25 'slots' long) aka a c 'string' if you terminate correctly (ie '\0')
iirc, if you initialise a ptr-to-char during a declaration, that makes it a constant ?
It's been a while and I don't have my books handy.

In your description I think you confuse minimum with maximum.
I don't understand the line did you mean

sprintf(cRight, "%d", iRight);

Whats that line for? iRight has been given a string value immediately before, yet your trying to convert it to a string? (sprintf can not know that iRight is not a number, since you told it to expect a number, it will interpret the pointer as a number). There is also no garentee that the output will be 4 chars (for a total of 5 in the string). This leads to memory corruption in the surrounding data, which can easily lead to messed-up data that will cause a segfault.

Your using unsafe functions, in a unsafe mannor, and the requirement of no-less then 25 for the size is probably due to the program corrupting itself, and with a value of 25 it simply has more room to corrupt itself before it starts overriding memory that will cause a segfault.