Trying to understand arrays and pointers better need some input.

[OmegaSupreme]

When I compile why am I getting an unknown file size error for the last function. The array isn't defined so why is size an issue?

include "stdafx.h"


void text_test(char text[]);
void text_test2( char *ptrtext);
void text_test3( char *array);
 int main()

{
    text_test("hello");
    text_test2("world");
    text_test3("again");
    
return 0;

}

void text_test(char text[])
{
    //char text[128];
    //ptrtext=text;

     printf("%s\n",text);
}

void text_test2( char *ptrtext)
{

    //char 2text[];
    //*ptrtext=2text;
    
    printf("%s\n",ptrtext);
}

void text_test3( char *array)
{
    char char_array[];
      *array = char_array[];

        printf("%s\n",char_array);
}

[iMalc]

"isn't defined"?! It's not just defined, it's declared right there on line 37, but in such a way that it will generate a compile error because the size is not specified and initialisation data is not provided.

WHat do you want it to do?

[OmegaSupreme]

"isn't defined"?! It's not just defined, it's declared right there on line 37, but in such a way that it will generate a compile error because the size is not specified and initialization data is not provided.

WHat do you want it to do?

I was just trying to get again to print using by setting pointer equal to an array. What kind of initialization is need to make it work?

[ZuK]

I was just trying to get again to print

void text_test3( char *array)
{
      char char_array[5];    // create an array
      *array = char_array[]; // the wrong way around
      char_array = array;    // not allowed to assign to an array
      printf("%s\n",char_array);
}

So , No that can't be done using assignment you need to call strcpy()

void text_test3( char *array)
{
      char char_array[5];
      strcpy( char_array, array );
      printf("%s\n",char_array);
}

Kurt

[AndiPersti]

void text_test3( char *array)
{
      char char_array[5];
      strcpy( char_array, array );
      printf("%s\n",char_array);
}

char_array[5] will be too small if the OP wants to call text_test3() with the string literal "again".

Bye, Andreas

[KenJackson]

It's safer to use strncpy().

void text_test3(char *array)
{
    char char_array[40];
    strncpy(char_array, array, sizeof(char_array));
    char_array[sizeof(char_array) - 1] = 0;     /* Because strncpy() doesn't terminate on overflow */
    printf("%s\n", char_array);
}

[OmegaSupreme]

It's safer to use strncpy().

void text_test3(char *array)
{
    char char_array[40];
    strncpy(char_array, array, sizeof(char_array));
    char_array[sizeof(char_array) - 1] = 0;     /* Because strncpy() doesn't terminate on overflow */
    printf("%s\n", char_array);
}

Thank you!