c语言 打印一个菱形

#include<stdio.h>
int diamond(int n,char c)
{
    int i,j,v,t;
    t=n/2;
    for(i=1;i<=t;i++){
        for(j=1;j<=t+1-i;j++)
            printf(" ");
        for(v=1;v<=2*i-1;v++)
                printf("%c",c);
            printf("\n");
    }
    for(i=t+1;i>=1;i--){
        for(j=0;j<=t-i;j++)
           printf(" ");
        for(v=1;v<=2*i-1;v++)
            printf("%c",c);
            printf("\n");
        }
        return 0;
}
int is_even(int n)
{
    if (n%2==0)
        return 1;
    else
        return 0;
}
int main(void)
{
    int num;
    char ch;
    printf("Please input a num and a char:\n");
    scanf("%d %c",&num,&ch);
    if(is_even(num)||num<=0){
        printf("The num is error!Please input again\n");
        scanf("%d %c",&num,&ch);
    }
    diamond(num,ch);
    return 0;
}