Thread: Problem with printf and scanf!

Hi everybody!
I have a project just received by today. It is pretty simple. Basically, just write a program about filling an information form and then print it out. (Using scanf and printf only)
Here is how i want it to be like: (notice the underlines are the input information)

First Name and Last Name:
Tommy John
Birth Of Date:
November 2 1987
Phone Number:
123456789
Hobbies:
Play soccer, reading and coding

Tommy John
November 2, 1987
123456789
Play soccer, reading and coding


And here is what i code:

Code:

#include <stdio.h>

int main()
{
    
    char firstname, lastname;
    char month;
    char hobbies;
    int day, year;
    double phonenumber;
    
    printf("First Name and Last Name:\n");
    scanf("&#37;s %s", &firstname, &lastname);
    
    printf("Birth Of Date:\n");
    scanf("%s %i %i", &month, &day, &year);
    
    printf("Phone Number:\n");
    scanf("%d", &phonenumber);
    
    printf("Hobbies:\n");
    scanf("%s", &hobbies);
    printf("\n");
    
    printf("%s %s", firstname, lastname);
    printf("%s %i %i", month, day, year);
    printf("%d", phonenumber);
    printf("%s", hobbies);
    
    

    system( "Pause" );
    return 0;
}

the problem i have is i was able to input through the last information which is hobbies, but it got crash and was unable to print out the information. And here is how the program and the crash message look like:
http://i35.tinypic.com/20hk0sy.jpg

i hope that somebody could help me out with this, because i already try out many way to fix the problem, but useless!

Once you figure out this character array thing (that must be like page 2 of chapter one), you'll have two choices -- either allocate enough storage with your declarations, or you can go the more exiting route, which is to use a buffer and malloc the space. That gives you the opportunity to learn about functions too:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char *assign (char *string) {
	char *ptr=malloc(strlen(string)+1);
	if (assign==NULL) {
		puts("malloc failure!");
		exit (-1);		// this is really unlikely
	} 
	strcpy(ptr,string);
	return ptr;
}


int main()
{
	char *firstname, *lastname, *month, *hobbies, *phonenumber, buffer1[4096], buffer2[4096];
	int day, year;

	printf("First Name and Last Name:\n");
	scanf("&#37;s %s", &buffer1, &buffer2);
	firstname=assign(buffer1);
	lastname=assign(buffer2);

	printf("Birth Of Date:\n");
	scanf("%s %i %i", &buffer1, &day, &year);
	month=assign(buffer1);

	printf("Phone Number:\n");
	scanf("%s", &buffer1);
	phonenumber=assign(buffer1);

	printf("Hobbies:\n");
	scanf("%s", &buffer1);
	hobbies=assign(buffer1);

	printf("\n%s %s\n", firstname, lastname);
	printf("%s %i %i\n", month, day, year);
	printf("%s\n", phonenumber);
	printf("%s\n", hobbies);

	free(firstname);	// remember to free char* that have
	free(lastname);		// been malloc'd
	free(month);
	free(hobbies);
	free(phonenumber);
	return 0;
}

Since you are not using the phone number in any arithmetic, there is really no point in storing it as some form of int. It may seem simpler to just go

Code:

char firstname[20], lastname[20], phonenumber[9], //etc

but you might as well learn about memory allocation as this is a crucial aspect of c programming. The buffers could be ten times smaller, but they are still only 4k of memory, and this way you have basically no chance of an overflow. If you seperate first and last name into two questions, you only need the one buffer.