void main(){
    for(;;){//循环作用一直判断c—调用不同的方法
        system("cls");
        float x,y;
        char con;
        int c,m;//c控制调用的方法
        fun1(); /* 调用菜单函数 */
            printf("输入你想要进行的运算(1~11):"                );
            scanf("%d",&c);
            if(c==1||c==2||c==3||c==4){
                do{
                    printf("请输入两个数:");
                    scanf("%f%f",&x,&y);//float类型的两个变量
                    fun2(x,y,c); /* 调用加减乘除函数—传递参数 */
                    printf("是否继续运行Y\n");
                    con=getch();
                }while(con=='y'||con=='Y');
            }else if(c==5||c==6){
                char con;
                do{
                    if(c==5){
                        printf("请输入底数和指数:");
                        scanf("%f%f",&x,&y);
                    }else{
                        printf("请输入一个数:");
                        scanf("%f",&x);
                    }
                    if(x<0) printf(" 输入错误!");
                        else fun3(x,y,c); /* 调用乘方开方函数 */
                    printf("是否继续运行Y/N\n");
                    con=getch();   
                }while(con=='y'||con=='Y');
            }else if(c==7) {
                char con;
                int l;
                do{
                    printf("请输入一个数:");
                    scanf("%d", &m);
                    printf("请输入要转换的进制(2、8、16):");
                    scanf("%d",&l);
                    convert(m,l); /* 调用进制转换函数 */
                    printf("是否继续运行Y/N\n");
                    con=getch();   
                }while(con=='y'||con=='Y');
            }else if(c==8) {
                char con;
                do{
                    printf("请输入一个数:");
                    scanf("%f",&x);
                    fun4(x); /* 调用求绝对值函数 */
                    printf("是否继续运行Y/N\n");
                    con=getch();   
                }while(con=='y'||con=='Y');
            }else if(c==9){
                printf(" <<<<<<<<<<<拜拜!謝謝使用哈!>>>>>>>>>>> \n");
                system("pause");
                quit();
            }else{
                printf(" <<<<<<<<<<输入错误>>>>>>>>>>> \n");
               
            }
            getch();
    }   
}
这里边只有第一次输入错误就无限循环错误，怎么修改