Passing String to Main from a function - c

Question

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
void get_name();
void display_name(char *fullname);
int main(void)
{
char first[80];
char second[80];
char *fullname[80];
get_name();
display_name(*fullname);
system("pause");
return 0;
}
void get_name()
{
char first[80];
char second[80];
char *fullname[80];
printf("Please enter first name: ");
scanf("%s", &first);
printf("\nPlease enter last name: ");
scanf("%s", &second);
strcpy(*fullname, first);
strcat(*fullname, " ");
strcat(*fullname, second);
printf("\n\nFull name is : %s ", *fullname);
}
void display_name(char *fullname)
{
int index;
char check;
int count=0;
printf("\n\nFull name is : %s ", fullname); //check to see if string is passes correctly
for(index=0; fullname[index] != '\0'; index++)
{
check=fullname[index];
if(check != ' ')
{
count++;
}
}
printf("\n\nNumber of characters in string is: %i\n", count);
}
im trying to send the string from get_name() to display name to count the number of characters. Everytime i pass the string, its comes out as gibberish. Am i passing wrong? I need to use one function to get the first and last name and concatenate the full name, then use another function to count the number of characters.

Answer 1

You're using pointers and scanf quite wrongly.
First of all scanf argument to for %s is supposed to be an array of characters. Remember that the array is in fact the pointer to the array.
Second you declare fullname to be an array of 80 pointers which is probably not what you want to do. Especially when you don't allocate the space for the string.
Instead it should be something like:
void get_name()
{
char first[80];
char second[80];
char fullname[80]; // an array of chars instead of pointers
printf("Please enter first name: ");
scanf("%s", first); // not taking the address of first - is already an address
printf("\nPlease enter last name: ");
scanf("%s", second); // not taking the address of second - is already an address
strcpy(fullname, first); // don't dereference fullname
strcat(fullname, " "); // don't dereference fullname
strcat(fullname, second); // don't dereference fullname
printf("\n\nFull name is : %s ", fullname); // don't dereference fullname
}

Answer 2

The declarations of variables are local to the scope where they are declared.
IOW when you declare first, second and fullname in your function get_name, they are local to that function. In order to pass the value outside of the function you have two, no three ways to do this starting with the worst way:
(1) declare the variable global, i.e. outside of main then share that variable in your function(s).
(2) declare the variable in main but pass it to the function who then fills in the string
int main()
{
char fullname[80];
get_name(fullname,sizeof(fullname)); // good to tell function avail size
...
void get_name(char* fullname, size_t length)
{
...
(3) Allocate memory on the heap, heap memory can be passed around between functions via a pointer
int main()
{
char* fullname = NULL;
get_name(&fullname);
...
void get_name(char** fullname)
{
*fullname = malloc(80);
...
EDIT
In order to read strings from the keyboard it is better to use fgets()
char buffer[128];
if (fgets(buffer,sizeof(buffer),stdin) != NULL) {
// remove the \n
char* p = strchr(buffer,'\n');
if ( p != NULL ) {
*p = '\0';
}
}
Using scanf reading from the keyboard is to be avoided, if you need to extract information use instead sscanf on the string read with fgets