求一个圆的面积，但是书上的可执行代码是0，不知道为什么

includedefinePI3.14159doubleArea(doubler);intmain(){doubleRadii,s;printf("请输入圆的半径：");scanf("%1f",&Radii);s=Area(Radii);printf("半径为%的圆的面积1f是%1f\n",半径,s);return0;}doubleArea(doubler){doubles;s=PI*r*r;returns;}https://gitee.com/wangfa23/fg...https://gitee.com/wangfa23/fg...https://gitee.com/wangfa23/fg...https://gitee.com/wangfa23/fg...https://gitee.com/wangfa23/fg...https://gitee.com/wangfa23/fg...https://gitee.com/wangfa23/fg...https://gitee.com/wangfa23/fg...https://gitee.com/wangfa23/fg...