使用浮点常量和变量的“printf”参数 1 的类型不兼容

Question

我正在尝试编写一个简单的 C 程序来模拟使用固定价格常量的购物体验，然后要求用户输入他们想要购买的金额。然后将数量和价格相乘以获得总成本。

#define TSHIRT   18.95f
//TSHIRT is a constant float for a fixed price on the cost of a t-shirt

int main(void) {
  float numberOfShirts;
  printf("How many T-Shirts would you like?");
  fflush( stdout);
  scanf("%f", &numberOfShirts);
  printf("You will receive %f shirt(s)", numberOfShirts);
  fflush( stdout);

  //This gets the user's amount of shirts they'd like to buy

  float totalCost = (numberOfShirts * TSHIRT);  //Edit: float totalCostadded
  printf("%f", totalCost);

  //this is supposed to be the total cost (amount * price) and print it, 
  //but I get an error -- "incompatible type for argument 1 of 'printf ".

如何修复它或获得正确的类型以使其正常工作？

Answer 1

您没有定义“totalCost”。确保它也是一个浮点数。顺便说一句，你所做的有点冒险，在你的 scanf 中捕获一个浮点数，如果用户不小心输入了一个字母，你的程序就会崩溃。更好的是从 scanf 接收一个字符串，然后检查其内容并将其转换为浮动，或者向用户报告错误。

Answer 2

您的代码中有各种错误：您没有声明变量totalCost，将其声明为float 可以解决您的类型问题。 您还需要包含 stdio.h 并且缺少右括号。 这个版本适合我：

#include <stdio.h>
#define TSHIRT   18.95f
//TSHIRT is a constant float for a fixed price on the cost of a t-shirt

int main(void) {
    float numberOfShirts;
    printf("How many T-Shirts would you like?");
    fflush( stdout );
    scanf("%f", &numberOfShirts);
    printf("You will receive %f shirt(s)",numberOfShirts);
    fflush( stdout );

    //This gets the user's amount of shirts they'd like to buy

    float totalCost = (numberOfShirts * TSHIRT);
    printf("%f", totalCost);
}