tk5-c90-projects/src/TXTWKR01.c

#include <stdio.h>

int main()
{
    printf("Starting program - attempting fopen(dd:TESTDD, \"r\")\n");

    FILE *fp = fopen("dd:TESTDD", "r");
    if (fp == NULL) {
        printf("fopen returned NULL\n");
        perror("fopen error");
        return 1;
    }

    printf("fopen succeeded!\n");
    /* rest unchanged */
}