结构点未由gcc识别 [英] struct point not identified by gcc
问题描述
我用一个名为point的3D坐标写了一个简单的程序。我是
加两点，占用他们的距离等.gcc编译器不是
识别结构。这是代码。我收到一堆错误。
主要是：在空声明中使用无用的存储类说明符，
''指''未声明（在此函数中首次使用），''p1''未声明
（首次使用此功能）等任何帮助将不胜感激。谢谢
#include< stdio.h>
#include< math.h>
/ *创建一个3d点结构* /
typedef结构点{
int x，y，z;
};
/ *函数声明* /
float dist（点*，点*）;
点add（点*，点*）;
无效显示（点*）;
int main（无效）
{
点p1 ，p2，p3;
p1.x = 2; p1.y = 4; p1.z = 5;
p2.x = 5; p1.y = 2 ; p1.z = 6;
printf（" \\\
dist =％f"，dist（& p1，& p2））;
add（ & p1，& p2）;
显示（& p3）;
返回;
}
float dist（点* a，点* b）
{
浮动长度= 0.0;
长度= sqrt（ （a-> xb-> x）*（a-> xb-> x）+（a-> yb-> y）*（a-> yb-> y）+
（a-> zb-> z）*（a-> zb-> z））;
返回长度;
}
点加（点* a，点* b）
{
点温度;
temp.x = a-> x + b-> x;
temp。 y = a-> y + b-> y;
temp.z = a-> z + b-> z;
返回temp; < br $>
}
无效显示（点* a）
{
printf（" \ npoint =％d，％d，％d \ n"，a-> x，a-> y，a-> z）;
}
I wrote a simply program with a 3 D coordinate called point. I am
adding two points, taking their distance etc. gcc compiler is not
identifying the struct. Here is the code. I get bunch of errors. The
main ones are : useless storage class specifier in empty declaration,
''point'' undeclared (first use in this function), ''p1'' undeclared
(first use in this function) etc. Any help will be appreciated. Thanks
#include <stdio.h>
#include <math.h>
/* create a 3d point struct*/
typedef struct point{
int x,y,z;
};
/* Function declaration*/
float dist(point *, point *);
point add(point *, point *);
void display(point *);
int main(void)
{
point p1,p2,p3;
p1.x=2;p1.y=4;p1.z=5;
p2.x=5;p1.y=2;p1.z=6;
printf("\n dist = %f", dist(&p1,&p2));
add(&p1, &p2);
display(&p3);
return;
}
float dist(point *a, point *b)
{
float length=0.0;
length = sqrt( (a->x-b->x)*(a->x-b->x)+ (a->y-b->y)*(a->y-b->y)+
(a->z-b->z)*(a->z-b->z));
return length;
}
point add(point *a, point *b)
{
point temp;
temp.x=a->x + b->x;
temp.y=a->y + b->y;
temp.z=a->z + b->z;
return temp;
}
void display(point *a)
{
printf("\npoint= %d,%d,%d\n",a->x,a->y,a->z);
}
推荐答案
2月22日上午9:27，DanielJohnson < diffuse ... @ gmail.comwrote：
On Feb 22, 9:27 am, "DanielJohnson" <diffuse...@gmail.comwrote:
我写了一个名为point的3D坐标的简单程序。我是
加两点，占用他们的距离等.gcc编译器不是
识别结构。这是代码。我收到一堆错误。
主要是：在空声明中使用无用的存储类说明符，
''指''未声明（在此函数中首次使用），''p1''未声明
（首次使用此功能）等任何帮助将不胜感激。谢谢
#include< stdio.h>
#include< math.h>
/ *创建一个3d点结构* /
typedef结构点{
int x，y，z;
};
/ *函数声明* /
float dist（点*，点*）;
点添加（点*，点*）;
void display（point *）;
I wrote a simply program with a 3 D coordinate called point. I am
adding two points, taking their distance etc. gcc compiler is not
identifying the struct. Here is the code. I get bunch of errors. The
main ones are : useless storage class specifier in empty declaration,
''point'' undeclared (first use in this function), ''p1'' undeclared
(first use in this function) etc. Any help will be appreciated. Thanks
#include <stdio.h>
#include <math.h>
/* create a 3d point struct*/
typedef struct point{
int x,y,z;
};
/* Function declaration*/
float dist(point *, point *);
point add(point *, point *);
void display(point *);
尝试：
typedef struct tag_point {
int x，y，z;
} point;
Try:
typedef struct tag_point {
int x,y,z;
} point;
>来自C FAQ：
>From the C FAQ:
第2节。结构，工会和枚举
2.1：这两个声明之间有什么区别？
struct x1 {...};
typedef struct {...} x2;
答：第一个表格声明了一个结构标签;第二个声明了一个
" typedef"。主要区别在于您随后将第一种类型称为struct x1并将第一种类型称为struct x1。第二个简单地称为x2。
也就是说，第二个声明是一个稍微抽象的b / b $ b类型 - 它的用户不一定知道它是一个结构，
并且在声明它的实例时不使用关键字struct。
2.2：为什么不
< br $>
struct x {...};
x thestruct;
工作？
答：C不是C ++。
结构标记不会自动生成Typedef名称。另见上面的问题2.1。
[snip]
Section 2. Structures, Unions, and Enumerations
2.1: What''s the difference between these two declarations?
struct x1 { ... };
typedef struct { ... } x2;
A: The first form declares a "structure tag"; the second declares a
"typedef". The main difference is that you subsequently refer
to the first type as "struct x1" and the second simply as "x2".
That is, the second declaration is of a slightly more abstract
type -- its users don''t necessarily know that it is a structure,
and the keyword struct is not used when declaring instances of it.
2.2: Why doesn''t
struct x { ... };
x thestruct;
work?
A: C is not C++. Typedef names are not automatically generated for
structure tags. See also question 2.1 above.
[snip]
DanielJohnson写道：
DanielJohnson wrote:
我写了一个名为point的3D坐标的简单程序。我是
加两点，占用他们的距离等.gcc编译器不是
识别结构。这是代码。我收到一堆错误。
主要是：在空声明中使用无用的存储类说明符，
''指''未声明（在此函数中首次使用），''p1''未声明
（首次使用此功能）等任何帮助将不胜感激。谢谢
#include< stdio.h>
#include< math.h>
/ *创建一个3d点结构* /
typedef结构点{
int x，y，z;
};
I wrote a simply program with a 3 D coordinate called point. I am
adding two points, taking their distance etc. gcc compiler is not
identifying the struct. Here is the code. I get bunch of errors. The
main ones are : useless storage class specifier in empty declaration,
''point'' undeclared (first use in this function), ''p1'' undeclared
(first use in this function) etc. Any help will be appreciated. Thanks
#include <stdio.h>
#include <math.h>
/* create a 3d point struct*/
typedef struct point{
int x,y,z;
};
更改为：
typedef struct {
int x;
int y;
int z;
} point;
Change this to:
typedef struct {
int x;
int y;
int z;
} point;
/ *函数声明* /
float dist（点*，点*）;
点加（点*，点*）;
无效显示（点* ）;
int main（无效）
{
点p1，p2，p3;
p1.x = 2; p1.y = 4; p1.z = 5;
p2.x = 5; p1.y = 2; p1.z = 6;
/* Function declaration*/
float dist(point *, point *);
point add(point *, point *);
void display(point *);
int main(void)
{
point p1,p2,p3;
p1.x=2;p1.y=4;p1.z=5;
p2.x=5;p1.y=2;p1.z=6;
为什么不使用更多的空格来帮助清晰？您似乎也在
覆盖p1.y和p1.z中的值。
Why not use more whitespace to aid in clarity? You also seem to be
overwriting the values in p1.y and p1.z.
printf（" \\\
dist = ％f"，dist（& p1，& p2））;
printf("\n dist = %f", dist(&p1,&p2));
在％f之后添加换行符。另外，根据上面给出的初始化结果，p2.y，p2.z，p3.x，p3.y，p3.z都是未初始化的。如果你使用未初始化的物品操作
，你很可能会回来无用
结果。
Add a newline after %f as well. Also as per the initialisations given
above, p2.y, p2.z, p3.x, p3.y, p3.z are all uninitialised. If you
operate on uninitialised objects you''ll most likely get back useless
results.
add （& p1，& p2）;
add(&p1, &p2);
函数add返回一个本地对象（如下所示）。你不是在这里给任何东西分配返回值，从而失去它。
The function add returns a local object, (as given below). You''re not
assigning the return value to anything here, thus loosing it.
display（& p3）;
返回;
display(&p3);
return;
返回一个显式值;不要返回随机值。
Return an explicit value; don''t return random values.
}
float dist（point * a，point * b）
{
浮动长度= 0.0;
长度= sqrt（（a-> xb-> x）*（a-> xb - > x）+（a-> yb-> y）*（a-> yb-> y）+
（a-> zb-> z）* （A-> ZB-&将Z））;
}
float dist(point *a, point *b)
{
float length=0.0;
length = sqrt( (a->x-b->x)*(a->x-b->x)+ (a->y-b->y)*(a->y-b->y)+
(a->z-b->z)*(a->z-b->z));
您确实意识到b-> y和b-> z未初始化不是吗？你可能还想把凌乱的函数调用分成更可读的步骤。
You do realise that b->y and b->z are uninitialised don''t you? You
might also want to split up the messy function call into more readable
steps.
返回长度;
}
点加（点* a，点* b）
{
点温度;
temp.x = a-> x + b-> x;
temp.y = a-> y + b-> y ;
temp.z = a-> z + b-> z;
返回临时数;
}
无效显示（点* a）
{
printf（" \ npoint =％d，％d，％d \ n" ;，a-> x，a-> y，a-> z）;
}
return length;
}
point add(point *a, point *b)
{
point temp;
temp.x=a->x + b->x;
temp.y=a->y + b->y;
temp.z=a->z + b->z;
return temp;
}
void display(point *a)
{
printf("\npoint= %d,%d,%d\n",a->x,a->y,a->z);
}
纠正这些错误，尝试再次编译。
Correct these errors and try to compile again.
2月22日，下午12:43，santosh < santosh .... @ gmail.comwrote：
On Feb 22, 12:43 pm, "santosh" <santosh....@gmail.comwrote:
DanielJohnson写道：
DanielJohnson wrote:
我写了一个只需使用称为点的3D坐标编程。我是
加两点，占用他们的距离等.gcc编译器不是
识别结构。这是代码。我收到一堆错误。
主要是：在空声明中使用无用的存储类说明符，
''指''未声明（在此函数中首次使用），''p1''未声明
（首次使用此功能）等任何帮助将不胜感激。谢谢
I wrote a simply program with a 3 D coordinate called point. I am
adding two points, taking their distance etc. gcc compiler is not
identifying the struct. Here is the code. I get bunch of errors. The
main ones are : useless storage class specifier in empty declaration,
''point'' undeclared (first use in this function), ''p1'' undeclared
(first use in this function) etc. Any help will be appreciated. Thanks
#include< stdio.h>
#include< math.h>
#include <stdio.h>
#include <math.h>
/ *创建一个3d点结构* /
typedef struct point {
int x，y，z;
};
/* create a 3d point struct*/
typedef struct point{
int x,y,z;
};
更改为：
typedef struct {
int x;
int y;
int z;
} point;
Change this to:
typedef struct {
int x;
int y;
int z;
} point;
/ *函数声明* /
float dist（点*，点*）;
点加（点*，点*）;
无效显示（点* ）;
/* Function declaration*/
float dist(point *, point *);
point add(point *, point *);
void display(point *);
int main（void）
{
point p1，p2，p3;
p1.x = 2; p1.y = 4; p1.z = 5;
p2.x = 5; p1.y = 2; p1.z = 6 ;
int main(void)
{
point p1,p2,p3;
p1.x=2;p1.y=4;p1.z=5;
p2.x=5;p1.y=2;p1.z=6;
为什么不使用更多的空格来帮助清晰？您似乎也在
覆盖p1.y和p1.z中的值。
Why not use more whitespace to aid in clarity? You also seem to be
overwriting the values in p1.y and p1.z.
printf（" \\\
dist = ％f"，dist（& p1，& p2））;
printf("\n dist = %f", dist(&p1,&p2));
在％f之后添加换行符。另外，根据上面给出的初始化结果，p2.y，p2.z，p3.x，p3.y，p3.z都是未初始化的。如果你使用未初始化的物品操作
，你很可能会回来无用
结果。
Add a newline after %f as well. Also as per the initialisations given
above, p2.y, p2.z, p3.x, p3.y, p3.z are all uninitialised. If you
operate on uninitialised objects you''ll most likely get back useless
results.
add （& p1，& p2）;
add(&p1, &p2);
函数add返回一个本地对象（如下所示）。你不是在这里给任何东西分配返回值，从而失去它。
The function add returns a local object, (as given below). You''re not
assigning the return value to anything here, thus loosing it.
display（& p3）;
返回;
display(&p3);
return;
返回一个显式值;不要返回随机值。
Return an explicit value; don''t return random values.
}
}
float dist（point * a，point * b）
{
浮动长度= 0.0;
长度= sqrt（（a-> xb-> x ）*（a-> xb-> x）+（a-> yb-> y）*（a-> yb-> y）+
（a-> ; ZB-&将Z）*（A-> ZB-&将Z））;
float dist(point *a, point *b)
{
float length=0.0;
length = sqrt( (a->x-b->x)*(a->x-b->x)+ (a->y-b->y)*(a->y-b->y)+
(a->z-b->z)*(a->z-b->z));
您确实意识到b-> y和b-> z未初始化不是吗？你可能还想把凌乱的函数调用分成更可读的步骤。
You do realise that b->y and b->z are uninitialised don''t you? You
might also want to split up the messy function call into more readable
steps.
返回长度;
}
return length;
}
point add（point * a，point * b）
{
点温度;
temp.x = a-> x + b-> x;
temp.y = a-> ; y + b-> y;
temp.z = a-> z + b-> z;
返回温度;
}
point add(point *a, point *b)
{
point temp;
temp.x=a->x + b->x;
temp.y=a->y + b->y;
temp.z=a->z + b->z;
return temp;
}
无效显示（点* a）
{
printf（" ; \ npoint =％d，％d，％d \ n"，a-> x，a-> y，a-> z）;
}
void display(point *a)
{
printf("\npoint= %d,%d,%d\n",a->x,a->y,a->z);
}
纠正这些错误并尝试再次编译。
Correct these errors and try to compile again.
我做了所有更改，现在我收到了这个错误
undefined reference tosqrt'
math.sqrt（）是正确的还是只是sqrt（）
I did all your changes and now I get this error
undefined reference to `sqrt''
Is math.sqrt() correct or just sqrt()
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