I am using freeBSD arm64 on my pi4 to test some C code. I am finding strange behavior.
I know that i should be doing the parsing a bit differently but I like to get the basics working first.

char* combineString(int num, ...) {
    
    char* finalStr;

    finalStr = calloc(600, sizeof(char));

    va_list vaList;
    
    /* initialize */

    va_start(vaList, num);

    printf("%i\n", num);

    for (int x = 0; x < num; num++) {

        char* str = va_arg(vaList, char*);

        strcat(finalStr, str);

        printf("%s\n", finalStr);
    }

    va_end(vaList);

    return finalStr;

}

Somehow, this program loops 5 times instead of 2 (the number of arguments I told the function I had).
The number of arguments is indicated by ‘num’.

combineString(2, "f", char* type here)

will produce:

f
fchartypehere
fchartypehere
fchartypehere
fchartypeherechartypehere

where the double chartypehere indicates it wrote that char* twice even though it should only be looping twice? I am using gcc to compile this and whenever i use gdb to get some relevant information i get this:

Program received signal SIGSEGV, Segmentation fault.
Address not mapped to object.
strcat (s=<optimized out>, append=<optimized out>) at /usr/src/lib/libc/string/strcat.c:46
46      /usr/src/lib/libc/string/strcat.c: No such file or directory.

I suppose its just coincedentally running 5 times due to undefined behavior but i am not sure where in my code exactly its causing that?