Troubles with scanf function (C)

Question

I have the following code:

struct punto richiedi_punto () {
static int count=1;
struct punto point;

do {
printf("Inserire coordinate del punto %i:", count);
scanf("%d;%d",&point.x,&point.y);

} while (point.x<0 || point.x>9 || point.y<0 || point.y>9);
count++;

return point;
}

Gcc doesn't find errors, but I get this warning:

Warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]

I tried to find out a solution on google, but I didn't understand what causes this warning.

Thanks in advance.

EDIT: I noticed just now that if I run my program in MonoDevelop console, I cannot insert my coordinates (why?), but if I run it in gnome-terminal it works normally.

Answer 1

scanf() returns the number of fields successfully converted, for you to check

int fields;
do {
    printf("Inserire coordinate del punto %i:", count);
    fields = scanf("%d;%d",&point.x,&point.y);
} while (fields != 2 || point.x<0 || point.x>9 || point.y<0 || point.y>9);

As @chux points out, the above is not good. Here is a version using sscanf instead of scanf.

#include <stdio.h>

int main()
{
    int fields, x, y;
    char inp[100];
    do {
        printf("Inserire coordinate:");
        fgets(inp, 100, stdin);
        fields = sscanf(inp, "%d;%d",&x,&y);
    } while (fields != 2 || x<0 || x>9 || y<0 || y>9);
    printf("x=%d, y=%d\n", x, y);
    return 0;
}