如下一段代码求解释。。。。

[极灿烂时光]

typedef struct tagCRDCARTESIAN{
double x;
double y;
double z;
}CRDCARTESIAN;
typedef CRDCARTESIAN *PCRDCARTESIAN;

这是在.h文件中的声明，不太清楚意思。

[赵4老师]

声明了两个类型别名CRDCARTESIAN和PCRDCARTESIAN 分别对应“结构tagCRDCARTESIAN”和“指向结构tagCRDCARTESIAN的指针” typedef typedef type-declaration synonym; The typedef keyword defines a synonym for the specified type-declaration. The identifier in the type-declaration becomes another name for the type, instead of naming an instance of the type. You cannot use the typedef specifier inside a function definition. A typedef declaration introduces a name that, within its scope, becomes a synonym for the type given by the decl-specifiers portion of the declaration. In contrast to the class, struct, union, and enum declarations, typedef declarations do not introduce new types — they introduce new names for existing types. Example // Example of the typedef keyword typedef unsigned long ulong; ulong ul; // Equivalent to "unsigned long ul;" typedef struct mystructtag { int i; float f; char c; } mystruct; mystruct ms; // Equivalent to "struct mystructtag ms;" typedef int (*funcptr)(); // funcptr is synonym for "pointer // to function returning int" funcptr table[10]; // Equivalent to "int (*table[10])();"

[小雨好赖床]

意思就是说 CRDCARTESIAN tagCrdcartesian; == struct tagCRDCARTESIAN tagCrdcartesian; PCRDCARTESIAN ptagCrdcartesian; == struct tagCRDCARTESIAN * ptagCrdcartesian; 这样定义两个变量 上面是结构体

[极灿烂时光]

引用 1 楼 zhao4zhong1 的回复:

声明了两个类型别名CRDCARTESIAN和PCRDCARTESIAN 分别对应“结构tagCRDCARTESIAN”和“指向结构tagCRDCARTESIAN的指针” typedef typedef type-declaration synonym; The typedef keyword defines a synonym for the specified type-declaration. The identifier in the type-declaration becomes another name for the type, instead of naming an instance of the type. You cannot use the typedef specifier inside a function definition. A typedef declaration introduces a name that, within its scope, becomes a synonym for the type given by the decl-specifiers portion of the declaration. In contrast to the class, struct, union, and enum declarations, typedef declarations do not introduce new types — they introduce new names for existing types. Example // Example of the typedef keyword typedef unsigned long ulong; ulong ul; // Equivalent to "unsigned long ul;" typedef struct mystructtag { int i; float f; char c; } mystruct; mystruct ms; // Equivalent to "struct mystructtag ms;" typedef int (*funcptr)(); // funcptr is synonym for "pointer // to function returning int" funcptr table[10]; // Equivalent to "int (*table[10])();"

谢谢！那么，在调用时应该怎么用呢？比如如何在Main函数中初始化一个结构体及其指针，然后调用函数。 函数定义为：Aaa(PCRDGEODETIC pcg, PCRDCARTESIAN pcc,double dSemiMajorAxis, double dFlattening);

[buyong]

Aaa(PCRDGEODETIC pcg, PCRDCARTESIAN pcc,double dSemiMajorAxis, double dFlattening); 你要知道这些是输入参数还是输出参数，查手册吧。 最简单的：

CRDGEODETIC cg;
CRDCARTESIAN cc;
Aaa(&cg, &cc, 0,0);