problem accessing a value in a structure

**buetxxth** · 02-09-2010

Hi all,

I am getting ready to start a project which entails implementing an array adt. To get started and train a bit I have made a structure for testing purposes which is giving me problems.

More concretely when I compile the whole stuff the compiler tells me that there is an error in the lines that I have commented below. The error says ' incompatible types in assignment'. I have tried removing the scanf's and assigning the values manually like this :

Code:

       emp1.name = "paul";
       emp1.address = "lexinton ave.";

but I get the same error. Can anyone give me a hand? I post the code below. Cheers!!

Code:

/*
 * test1.c
 *
 *  Created on: Feb 9, 2010
 *      Author
 */

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

int main(void) {

	char myname[30];
	char myaddress[100];
	int myage;
	float mysalary;

	struct employee {
		char name[30];
		char address[100];
		int age;
		float salary;
	} emp1, emp2;

	printf("Enter the name of the employee: ");
	scanf("%s", myname);
	printf("Enter the address of the employee: ");
	scanf("%s", myaddress);
	printf("Enter the age of the employee: ");
	scanf("%d", &myage);
	printf("Enter the salary of the employee: ");
	scanf("%f", &mysalary);

	printf("the age of emp1 is: %s\n", emp1.name);
	printf("the age of emp1 is: %s\n", emp1.address);
	printf("the age of emp1 is: %d\n", emp1.age);
	printf("the salary of emp1 is: %f\n", emp1.salary);

	emp1.name = myname; // error: Incompatible types in assignment
	emp1.address = myaddress; //error: Incompatible types in assignment
	emp1.age = myage;
	emp1.salary = mysalary;

	emp1 = emp2;

	return 0;
}

**Salem** · 02-09-2010

> emp1.name = myname; // error: Incompatible types in assignment
Use strcpy() to copy c-style strings.

**samf** · 02-09-2010

Salem is right. You may also want to add

Code:

#include <string.h>

I would also consider moving

Code:

printf("the age of emp1 is: %s\n", emp1.name);
printf("the age of emp1 is: %s\n", emp1.address);
printf("the age of emp1 is: %d\n", emp1.age);
printf("the salary of emp1 is: %f\n", emp1.salary);

after

Code:

strcpy(emp1.name, myname);
strcpy(emp1.address, myaddress);
emp1.age = myage;
emp1.salary = mysalary;

Printing something that has not been given a value is not a good idea.

Also

Code:

emp1 = emp2;

What is assigned to emp2? Do you mean

Code:

emp2 = emp1;

**buetxxth** · 02-11-2010

Hi there,

Thank you for the help!!

From the suggestion below I understand that the two variables within the structures that are having problems are the ones that have to do with characters.

Code:

strcpy(emp1.name, myname);
strcpy(emp1.address, myaddress);
emp1.age = myage;
emp1.salary = mysalary;

I see that the other two int within the structure have no problem in assigning them the value with scanf.

I realize see the problem with the order in which I wrote it. The printf's should have been after the value assignement. After the variable declarations, that is.

However I still don't understand why, If I have declared a string of 30 characters
I cannot use a scanf to store the value in a variable and then print it with an printf within the context of a structure:

example 1:

Code:

char name [30];
scanf("%s",name);
printf("the name is %s",name);

example 2:

Code:

	struct employee { // here we declare the structure
		char name[30];
		char address[100];
		int age;
		float salary;
	} emp1, emp2;

	printf("Enter the name of the employee: "); 
	scanf("%s", myname); 
	printf("Enter the address of the employee: ");
	scanf("%s", myaddress);
	printf("Enter the age of the employee: ");
	scanf("%d", &myage); // this has no problem
	printf("Enter the salary of the employee: ");
	scanf("%f", &mysalary); // this has no problem

	emp1.name = myname; // error: Incompatible types in assignment
	emp1.address = myaddress; //error: Incompatible types in assignment
	emp1.age = myage;
	emp1.salary = mysalary;

In 'example 2' I declared the structure and within it the chars that will take a value. Then I assigned them with scanf.

In example 1' there is no structure, I just declared the chars that will take a value.

Why does the char assignment (with scanf) work in example 1 and it does not work in example 2? I wander if it would work with getchar();??

Evidently the two int that I declared have no problem only the chars.

Why??

Thank you...

**MK27** · 02-11-2010

For the same reason you cannot do this:

Code:

char str1[]="hello world", str2[20] = str1;

If you want to copy the contents of a string, you must use a string function like strcpy() or sprintf().

You can assign a pointer to a string:

Code:

char str1[]="hello world", *ptr = str1;

I think what you want to do with that struct is just this:

Code:

	printf("Enter the name of the employee: "); 
	scanf("%s", emp1.name);

Simple enough?

**bluetxxth** · 02-11-2010

Hi MK,

That is exactly what I wanted ;-) The pointer, however, sounds much better. I am going to test it after a few experiments with this example.

BR,

Blue

**bluetxxth** · 02-11-2010

Hi again,

there is something seemingly wrong with the compiler I think. Now there is no error at all but it simply gives me an unexpected output.

I paste the code and the output here

Code:


/*
 * test1.c
 *
 *  Created on: Feb 9, 2010
 *      Author
 */

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

int main(void) {

	struct employee {
		char name[30];
		char address[100];
		int age;
		float salary;
	} emp1;


	printf("Enter the name of the employee: ");
	scanf("%s", emp1.name);
	printf("Enter the address of the employee: ");
	scanf("%s", emp1.address);
	printf("Enter the age of the employee: ");
	scanf("%d", &emp1.age);
	printf("Enter the salary of the employee: ");
	scanf("%f", &emp1.salary);


	printf("the age of emp1 is: %s\n", emp1.name);
	printf("the age of emp1 is: %s\n", emp1.address);
	printf("the age of emp1 is: %d\n", emp1.age);
	printf("the salary of emp1 is: %f\n", emp1.salary);


	return 0;
}

Here is the output:

Enter the name of the employee: Enter the address of the employee: Enter the age of the employee: Enter the salary of the employee: the age of emp1 is:
the age of emp1 is: @
the age of emp1 is: 280
the salary of emp1 is: 0.000000

It does not return what is expected plus I see that there is a message when I compile it that says

**** Build of configuration Debug for project test1 ****

**** Internal Builder is used for build ****
Nothing to build for test1

I use eclipse cpp.

Can anyone help?

br,

blue

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