这是我编的题目其中的一段
 #include <stdio.h>
int main(void)
{
    char kind;
    int mark=0;
    float a_pounds,b_pounds,c_pounds,allpounds,total,o_cost,pl_price;

    a_pounds=b_pounds=c_pounds=allpounds=pl_price=0;
    printf("Choose the vagetable you want to buy:\n");
    printf("a.artichoke.          b.beet.\n");
    printf("c.carrot.             q.quit.\n");
    while(scanf("%c",&kind))
    {
        switch(kind)
        {
    case'a':printf("Enter the pounds:\n");
             scanf("%f",&a_pounds);
             break;
    case'b':printf("Enter the pounds:\n");
             scanf("%f",&b_pounds);
            break;
    case'c':printf("Enter the pounds:\n");
             scanf("%f",&c_pounds);
            break;
    case'q':mark=1;
             break;
        }
        if(mark)
            break;
        printf("Choose another vagetable:\n");
    }
执行时为什么“Choose another vagetable:”这句话会输出两遍呢？实在不懂。
麻烦知道的解释一下，万分感谢！

后来想通了，主要是回车键算了一次字符，所以多循环了一次，谢谢各位了。