Question

I have the next C code:

#include <stdio.h>
#include <stdlib.h>
#include "list.h"
#include "graph.h"

int main() {
    int action, src, dst;
    IntGraph g;

    g = newIntGraph();

    while (1) {
        printf("1 -> Add a nodes.\n");
        printf("2 -> Add an arc.\n");
        printf("3 -> Dump the graph.\n");
        printf("4 -> BFS.\n");
        printf("What do you want to do? [1, 2, 3, 4] ");
        scanf("%d", &action);

        switch (action) {
            case 1:
                addIntGraphNode(&g);
                break;

            case 2:
                printf("Insert source and destination: ");
                scanf("%d", &src);
                scanf("%d", &dst);
                addIntGraphArc(&g, src, dst);
                break;

            case 3:
                dumpIntGraph(g, "GRAPH\0");
                break;

            case 4:
                printf("Insert the node to start: ");
                scanf("%d", &src);
                BFSIntGraph(g, src);
                break;

            default:
                return 0;
        }
    }
}

But I need it to do some test so I would like to have a ready input that will generate the base graph.

I wrote the input in a file (one number per line). I have a file with ten lines and ten 1, because I want the programm to generate a graph with ten nodes.

When I type:

./graph-test.run < input/graph-input.txt

It starts and endless reading from the file, adding hundreds nodes. I would like it to stop once the file is finished to let me do some other operation.

How can I accomplish this? The code works well if I insert the values manually, so it’s an input related problem.

Answer 1

For every call to scanf check if returns an EOF. In case of an EOF break out of while(1) loop.

if (EOF == scanf(....))
    break; //or exit(0);