c - 当我只从 int 切换到 double 时，为什么程序提供 -143155...？

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如果我使用 float 或 double 而不是 int，为什么这段代码会给出完全错误的答案？

//C How to Program Exercises 2.33
#include <stdio.h>
#include <conio.h>
double dailyDrivingCost(double miles, double costPerGallon,double averageMilesPerGallon);
int main(void){
    double a,b,c,d,e;
    printf ("Please enter the number of miles daily\n");
    scanf("%lf",&a);
    printf ("Please enter the cost per gallon\n");
    scanf("%lf",&b);
    printf ("Please enter the average miles per gallon\n");
    scanf("%lf",&c);
    printf ("The number of miles per gallon is:%d",dailyDrivingCost(a,b,c));
getch();
return 0;
}
double dailyDrivingCost(double miles, double costPerGallon,double averageMilesPerGallon){
      double overall_cost;
      overall_cost= (miles/averageMilesPerGallon)+ costPerGallon;

      return overall_cost;
}

Answer 1

改变

printf ("The number of miles per gallon is:%d",dailyDrivingCost(a,b,c));
                                            ^

到

printf ("The number of miles per gallon is:%f",dailyDrivingCost(a,b,c));

d 转换说明符用于打印 int、打印 double(或 float)您需要 f 转换说明符。