C语言详细讲解#error与#line如何使用

#include <stdio.h>
 
#ifndef __cplusplus
    #error This file should be processed with C++ compiler.
#endif
 
class CppClass
{
private:
    int m_value;
public:
    CppClass()
    {
        
    }
    
    ~CppClass()
    {
    }
};
 
int main()
{
    return 0;
}

#include <stdio.h>
 
void f()
{
#if ( PRODUCT == 1 )
    printf("This is a low level product!\n");
#elif ( PRODUCT == 2 )
    printf("This is a middle level product!\n");
#elif ( PRODUCT == 3 )
    printf("This is a high level product!\n");
#else
    #error The macro PRODUCT is NOT defined!
#endif
}
 
int main()
{
    f();
    
    printf("1. Query Information.\n");
    printf("2. Record Information.\n");
    printf("3. Delete Information.\n");
 
#if ( PRODUCT == 1 )
    printf("4. Exit.\n");
#elif ( PRODUCT == 2 )
    printf("4. High Level Query.\n");
    printf("5. Exit.\n");
#elif ( PRODUCT == 3 )
    printf("4. High Level Query.\n");
    printf("5. Mannul Service.\n");
    printf("6. Exit.\n");
#else
    #error The macro PRODUCT is NOT defined!
#endif
    
    return 0;
}

#include <stdio.h>
 
// The code section is written by A.
// Begin
#line 1 "a.c"
 
// End
 
// The code section is written by B.
// Begin
#line 1 "b.c"
 
// End
 
// The code section is written by AutumnZe.
// Begin
#line 1 "AutumnZe.c"

int main()
{
    printf("%s : %d\n", __FILE__, __LINE__);
    
    printf("%s : %d\n", __FILE__, __LINE__);
    
    return 0;
}
// End