c - 找出整数

Question

我试图让这段代码在有人输入负数甚至整数时给出错误。我有一个负整数，但我似乎找不到让系统在输入偶数时给出错误消息的方法。

#include <stdio.h>

int main(void){

    int size, i, j, spaces, stars, true, false;


    printf("How many rows do you want?\n"); //ask the user how many rows they want
    scanf("%d", &size);

    //this check to make sure a positive, odd integer is entered
    if(size <= 0)
        printf("sorry, but you need to input a positive, odd integer.\n");


    int mid = size/2 +1; //this is to find the midpoint of the diamond where you will start decrementing

    //menu options


    //this is the for loop that will create your rows
    for(i = 1; i <= size; i++){
            if(i < mid){
                spaces = mid - i;
                stars = size - (spaces*2);
            }
            if(i > mid){
                spaces = i - mid;
                stars = size - (spaces*2);
            }
            if (i == mid){
                spaces = 0;
                stars = size;
            }

        for(j = 0; j < spaces; j++)
            printf(" ");
        for(j = 0; j < stars; j++)
            printf("*");

        printf("\n");

    }
    return 0;
}

Answer 1

if(size % 2 == 0)
    printf("sorry, even integer not allowed.\n");