Question

Is it possible to return a char Pointer even the calling function is not in the same file…. if I call the function for example:

 void gotest(sqlite3 *pt,char *nutzers)
{
    char string[1064];
    char *text;
    text = get_data_byName(pt,"whatever",string);   
    printf("test %s \n\n\n same file",text);    
}

 char *get_data_byName(sqlite3 *ptr,char *user,char *resulter)
{
    .......
    resulter = "TestCall";
    return resulter;
}

if gotest(sqlite3 *pt,char *nutzers) and char *get_data_byName(sqlite3 *ptr,char *user,char *resulter) are in different files then gcc gives the following

Assignment makes pointer from integer without a cast

if I have both functions in one file everything works fine.

compiling like:

gcc -o test test.c time.c database.c libircclient-1.6/src/libircclient.o -lsqlite3 

Answer 1

You need headers for your files. If GCC doesn’t see a function prototype in the file it’s used in, GCC assumes that the function returns an int. You need to read up on headers. In the mean time, putting this in the file where you use get_data_byName will be enough:

char *get_data_byName(sqlite3 *ptr,char *user,char *resulter);

You have to remember that although when GCC is linking, it knows that you define get_data_byName, when it’s compiling, it needs to know what parameters and return values it has. That’s the purpose of a header. Headers contain function prototypes. A function prototype looks like this:

char *get_data_byName(sqlite3 *ptr,char *user,char *resulter);

If you put the prototypes of all of the functions defined in one .c file in one .h file, and them #include that header in the files that use the function, you wont get that error anymore. So if you have a file called get_data_by_name.c, this would be get_data_by_name.h:

#ifndef GET_DATA_BY_NAME_H
#define GET_DATA_BY_NAME_H
char *get_data_byName(sqlite3 *ptr,char *user,char *resulter);
#endif

Then just #include it in the file that uses get_data_byName:

#include "get_data_by_name.h"