Assume that i have two types of query one is 1 2 3 and the other one is 2 3

if the head (index 0) is 1, then the total number within the input are 3 (1 2 3) and if the head is 2 then the total number within the input are 2 number (2 9)

How do I detect it? Thank you

The problem that I have is that I scan the 3 of them scanf("%d %d %d",&a,&b&c)

so, when I only have total of 2 number in the input (2 3) The program wont continue

Thank you

CodePudding user response：

You use the return value of scanf() to detect this, and you should generally always check return values. They are given for a purpose.

#include <stdio.h>

int main(void) {
    int a;
    int b;
    int c;

    printf("Please enter 2 or 3 numbers: ");
    int n = scanf("%d%d%d", &a, &b, &c);
    switch (n) {
    case 2:
        printf("You have entered 2 numbers, %d and %d\n", a, b);
        break;
    case 3:
        printf("You have entered 3 numbers, %d, %d and %d\n", a, b, c);
        break;
    default:
        printf("Well, you made an error.\n");
        break;
    }
}

Note 1: Even printf() returns a value, commonly the number of characters printed. In this simple example, we can ignore it.

Note 2: It is always a very good idea to read the documentation of functions you use, if you don't know them in detail.