Thread: return values of functions

Well there are a couple of things wrong with what you're trying to do.

First, you've declared your function return type as type char. However, you're trying to return the array. These are incompatible types.

Second, you're really returning only the address of your array. That's how you return arrays anyways. However, your array is temporary and your array will be out of scope when you return. This will make the address returned invalid and this is dangerous because you may modify addresses you're not supposed to.

Thirdly, use fgets instead of scanf. This is safer because you can check the length.

A solution would be to declare your function return type as:
char * new_book()

Dynamically allocate some memory for your string and return it after you have filled it up with the data you want. You can always use a global char array to store the value though, but what would be the fun of that

This won't work, you can't return an array in C. You can fake it by returning a char *, but in this case it still won't work because when the function returns, the memory for fn is freed and the pointer that you pass back will point to garbage. The best way to do this is to have the calling function allocate an array and pass it to your function.

Code:

char *new_book( char fn[] )
{
        printf( "What do you want your new address book to be called: " );
        scanf( "%s", &fn );
        strcat( fn, ".dg" );

        return fn;
}

If you can't do that then you have to allocate the memory yourself and free it in the calling function.

Code:

char *new_book()
{
        char *fn = malloc( 104 );
        if( fn == NULL ) {
                fprintf( stderr, "Couldn't allocate memory\n" );
                return NULL;
        }

        printf( "What do you want your new address book to be called: " );
        scanf( "%s", &fn );
        strcat( fn, ".dg" );

        return fn;
}

make the array in main() or whereever and pass it into the function. arrays are passed by address so any changes you make to the array in your function will be available in main()

for instance....

Code:

#include<stdio.h>

void GetFileName(char[],int);

int main()
{
int SIZE=256;
char filename[SIZE]={0};
GetFileName(filename,SIZE);
printf("Your filename chosen is :- %s",filename);
return 0;
}

void GetFileName(char filename[],int sizeofbuffer)
{
// use fgets to get input into filename
// use strcat to concatenate .dz on end of filename
}