c - 从 C 中的类型分配给类型时出错，类型不兼容

Question

所以我正在为学校做作业，但我不断收到错误消息，并且我已经阅读了多个线程，但我还没有找到灵魂，或者也许我只是不明白所说的内容。

这是我的代码:

#include <stdio.h>

int main() {
//declare the variables
float radius, circumference;

radius = 0;

printf ("This program will calculate the circumference of a circle given the radius\n");

printf ("Please enter the radius of the circle:\n");
scanf ("%f", &radius);

circumference = calculate_circumference(radius);

printf ("The circumference of the circle is:\n", circumference);
return 0;
}

float calculate_circumferene (float circle_radius)
{

    float circle_circumference, PI;

    PI = 3.14159;

    circle_circumference = 2 * PI * circle_radius;

    return (circle_circumference);
}

以下是我收到的错误消息:

prog.c: In function 'main':
prog.c:21:18: warning: implicit declaration of function  'calculate_circumference' [-Wimplicit-function-declaration]
  circumference = calculate_circumference(radius);
              ^
prog.c:24:10: warning: too many arguments for format [-Wformat-extra-args]
  printf ("The circumference of the circle is:\n", circumference);
      ^
/home/j1N8a0/ccUei3id.o: In function `main':
prog.c:(.text.startup+0x45): undefined reference to `calculate_circumference'
collect2: error: ld returned 1 exit status

任何类型的帮助或为我指明正确的方向将不胜感激!

Answer 1

在使用函数之前必须先声明函数，并小心拼写错误。

尽管为 printf() 提供额外的参数并无害处，但您必须使用以 % 开头的格式说明符通过 printf( 打印变量中的数据)。

试试这个:

#include <stdio.h>

/* declare the function to use */
float calculate_circumference (float circle_radius);

int main() {
    //declare the variables
    float radius, circumference;

    radius = 0;

    printf ("This program will calculate the circumference of a circle given the radius\n");

    printf ("Please enter the radius of the circle:\n");
    scanf ("%f", &radius);

    circumference = calculate_circumference(radius);

    /* add format specifier to print the value */
    printf ("The circumference of the circle is: %f\n", circumference);
    return 0;
}

/* add "c" before last "e" of the function name */
float calculate_circumference (float circle_radius)
{

    float circle_circumference, PI;

    PI = 3.14159;

    circle_circumference = 2 * PI * circle_radius;

    return (circle_circumference);
}