衝突的類型和x的先前的聲明在這裏......什麼？

Question

我一直在自學下了幾個月，當我有時間，我遇到了一個問題，我不知道如何解決。

具體而言，當我嘗試編譯這個使用gcc，我得到：

 
geometry.c:8: error: conflicting types for ‘trapezoid’ 
geometry.c:7: note: previous declaration of ‘trapezoid’ was here 
geometry.c:48: error: conflicting types for ‘trapezoid’ 
geometry.c:7: note: previous declaration of ‘trapezoid’ was here 
geometry.c:119: error: conflicting types for ‘trapezoid_area’ 
geometry.c:59: note: previous implicit declaration of ‘trapezoid_area’ was here 
geometry.c: In function ‘cone_volume’: 
geometry.c:128: error: called object ‘3.14100000000000001421085471520200371742248535156e+0’ is not a function 
geometry.c: In function ‘cylinder_volume’: 
geometry.c:136: error: called object ‘3.14100000000000001421085471520200371742248535156e+0’ is not a function 

現在，我想我可能需要強制轉換的功能，但同樣，我不知道。

它看起來要讀取PI，我已經定義爲3.141，爲函數。有沒有一種方法可以避免使用幻數3.141（儘管它比其他幻數小得多）？

//Geometric formulae 
#include <stdio.h> 
#include <math.h> 

#define PI 3.141 

float trapezoid(float b1, float b2, float h); 
int trapezoid(); 
float sphere_volume(float r); 
int sphere(); 
float cone_volume(float r, float h); 
int cone(); 
float pyramid_volume(float b, float h); 
int pyramid(); 
float cylinder_volume(float r, float h); 
int cylinder(); 

int main(void) { 
     char selection = 0; 

     while(selection != 'q') { 
       printf("\t--Geometric Formulas--\n"); 
       printf("\tSelection an option from the menu: "); 
       scanf("%c", & selection); 
       switch(selection) { 
         case 1: //Trapezoid area 
           printf("%d", trapezoid()); 
           break; 
         case 2: //Sphere volume 
           printf("%d", sphere()); 
           break; 
         case 3: //Cone volume 
           printf("%d", cone()); 
           break; 
         case 4: //Pyramid volume 
           printf("%d", pyramid()); 
           break; 
         case 5: //Cylinder volume 
           printf("%d", cylinder()); 
           break; 
         default: 
           break; 
       } 
     } 
} 
//  --Shape Menus-- 
//Trapezoid 
int trapezoid() { 
     float h = 0, b1 = 0, b2 = 0; 
     float traparea; 

     printf("\tTrapezoid base 1: "); 
     scanf("%3f", &b1); 
     printf("\tTrapezoid base 2: "); 
     scanf("%3f", &b2); 
     printf("\tTrapezoid height: "); 
     scanf("%3f", &b2); 

     traparea = trapezoid_area(b1, b2, h); 

     printf("\tTrapezoid Area: %3f\n", traparea); } 

//Sphere 
int sphere() { 
     float r = 0; 
     float spherevol; 

     printf("\tSphere radius: "); 
     scanf("%f", &r); 

     spherevol = sphere_volume(r); 

     printf("\tSphere volume: %3f\n", spherevol); } 

//Cone 
int cone() { 
     float r = 0, h = 0; 
     float conevol; 

     printf("\tCone radius: "); 
     scanf("%f", &r); 
     printf("\tCone height: "); 
     scanf("%f", &h); 

     conevol = cone_volume(r, h); 

     printf("\tCone volume: %3f\n", conevol); } 

//Pyramid 
int pyramid() { 
     float b = 0, h = 0; 
     float pyramidvol; 

     printf("\tPyramid base: "); 
     scanf("%f", &b); 
     printf("\tPyramid height: "); 
     scanf("%f", &h); 

     pyramidvol = pyramid_volume(b, h); 

     printf("\tPyramid volume: %3f\n", pyramidvol); } 

//Cylinder 
int cylinder() { 
     float r = 0, h = 0; 
     float cylindervol; 

     printf("\tCylinder radius: "); 
     scanf("%f", &r); 
     printf("\tCylinder height: "); 
     scanf("%f", &h); 

     cylindervol = cylinder_volume(r, h); 

     printf("Cylinder volume: %3f", cylindervol); } 

//  --Geometric Formulas-- 
//Trapezoid Area Computation 
float trapezoid_area(float b1, float b2, float h) { 
     return ((b1 + b2) * h)/2; } 

//Sphere Volume Computation 
float sphere_volume(float r) { 
     return ((pow(r,3)) * (4 * PI))/3; } 

//Cone Volume Computatioin 
float cone_volume(float r, float h) { 
     return ((PI(pow(r,2)) * h))/3; } 

//Pyramid Volume Computation 
float pyramid_volume(float b, float h) { 
     return (b * h)/3; } 

//Cylinder Volume Computation 
float cylinder_volume(float r, float h) { 
     return (PI(pow(r,2))) * h; } 

Answer 1

任何他們那說有一個「隱」的定義：這可以通過聲明前就可以解決。例如，您預先聲明瞭浮動梯形和int梯形，但您未預先聲明trapezoid_area。正如其他人指出的那樣，你也不能像在C++中那樣在C中重載。

在你試圖做隱含乘法幾個領域 - 例如，PI（POW（R，2））應PI *（POW（R，2））。

Answer 2

您定義了兩次函數梯形。 C不是C++。您不能像C++中使用重載功能一樣定義具有不同簽名的相同函數。

Answer 3

您所看到的錯誤是因爲你與不同的簽名

float trapezoid(float b1, float b2, float h); 
int trapezoid(); 

根據您的其他定義，它看起來像第一trapezoid功能應該被命名爲trapezoid_volume

float trapezoid_volume(float b1, float b2, float h); 
int trapezoid(); 

定義兩次同樣的功能

Answer 4

#define PI 3.141 

float trapezoid(float b1, float b2, float h); 
int trapezoid(); 

我想你想

float trapezoid_volume(...); 
/*    ^^^^^^^     */ 

Answer 5

Ç不支持函數重載。 C++一樣。

而且由於您不小心將trapezoid_volume標爲trapezoid，您會收到編譯器錯誤。

Answer 6

要回答你的問題有關定義PI - 圓周率通常在math.h定義（如M_PI），但因爲它不是一部分FO實際的標準，你可能需要做一些配置，以獲取它。

例如，使用MSVC時，您需要定義_USE_MATH_DEFINES才能得到它。對於GNU C庫的信息，請參閱

• http://www.gnu.org/s/hello/manual/libc/Mathematical-Constants.html

• http://www.gnu.org/s/hello/manual/libc/Trig-Functions.html#Trig-Functions

  。

如果您的平臺沒有它，你可能要拋出類似以下內容的標題：

#ifndef 
#define M_PI 3.14159265358979323846264338327 
#endif