Thread: Scanning through a file in C

Originally Posted by haynesmk

The while loop is terminating when it reaches an instruction that starts with with a 'zero'.

The while loop keeps looping as long as fgets does not return a null pointer, which would happen when there is an input error or when end of file has been reached. The thing is, you are not actually making use of the array named line after fgets has read into it. My guess is that you want to use sscanf instead, e.g.,

Code:

void printAssembly(char fileName[])
{
    int inst = 0;
    int pc = 0;
    FILE *f;
    char line[2048];
 
    f = fopen(fileName, "r");
    if (!f)
    {
        /* handle/report file open error */
        return;
    }

    if (fscanf(f, "%x", &pc) == 1)
    {
        while (fgets(line, sizeof(line), f))
        {
            if (sscanf(line, "%x", &inst) == 1)
            {
                pc++;

                if (inst >> 12 == 1)
                {
                    printAdd(inst);
                }

                if (inst >> 12 == 5)
                {
                    printAnd(inst);
                }

                if (inst >> 12 == 0)
                {
                    printBr(inst, pc);
                }
            }
            else
            {
                /* handle/report file format error */
            }
        }
    }
    else
    {
        /* handle/report file format error */
    }

    fclose(f);
}

If the pc value is actually expected to be on a separate line, then you would do the same fgets + sscanf approach to extract it instead of calling fscanf.

By the way, the fileName parameter should be a pointer to const char instead of a pointer to char. You could also move that part to a wrapper function that handles opening and closing the file, thereby changing this function's task scope to focus on reading from the file and printing accordingly (i.e., printAssembly's parameter would be a FILE* instead).