how to I copy structure char variable into another char array

Question

struct student
{
    char name[50];
    int rollno;
    float marks;
};
int main()
{
    char nam[50];
    int i = 0, n=5;
    struct student s1[n];
    for(i=0;i<n;i++)
    {
       nam[i] = s1[i].name;
     }
}

In given code, I am unable to copy s1[i].name in nam[i], I tried all the copy function but it's giving me error every time.

Use `strcpy()`. This should be explained in every C tutorial on strings. — Barmar, Jan 12 '22 at 20:00
`nam` is just one string, not an array of strings. Why are you trying to copy 5 names into it? — Barmar, Jan 12 '22 at 20:01
`nam[i]` is just a single character. How do you expect to put a whole name there? What result are you trying to get? — Barmar, Jan 12 '22 at 20:02
@Bhavin Patil "I tried all the copy function but it's giving me error every time." As for me then I do not know all copy functions as you ::) — Vlad from Moscow, Jan 12 '22 at 20:02
You need to study arrays then pointers then strings, in that order. I wrote a beginner FAQ about C strings here: [Common string handling pitfalls in C programming](https://software.codidact.com/posts/284849) You've written beginner bug #1 in that FAQ. — Lundin, Jan 13 '22 at 08:53

score 0 · Answer 1 · answered Jan 12 '22 at 20:08

This ...

       nam[i] = s1[i].name;

... does not make sense because name[i] is one char, whereas s1[i].name is an array of 50 chars. Moreover, your loop is over the number of elements of s1 (5), which is much less than the number of elements of nam or s1[i].name.

Supposing that you really do want s1 to be an array of struct student as opposed to just one struct, you probably want to use strcpy(). However, you might want or need to use memcpy() (or an element by element copy loop) depending on the nature of the contents of s1 and its elements and any artificial requirements on the exercise.

The strcpy() variation would look like this:

       strcpy(nam, s1[i].name);
       // do something with nam ...

That depends on the source array to contain a null-terminated string, which is not guaranteed to be the case in the demo program, which never puts any data in s1 or its elements.

ryyker · Answer 2 · 2022-01-24T14:21:11.430

Lots of little things working against you in this code, eg the following...

int i = 0, n=5;
struct student s1[n];

...creates a variable length array of struct student, preventing an initializer from being a viable path. But if for the sake of illustration you can live with a non-VLA version, then try this:

//Use a hard-coded to `5`,  to create an array of 5 struct student, initialized as shown: 
struct student s1[5] = {{"name1"1, 1.0},("name2",2,2.0},{"name3",3,3.0},{"name4",4,4.0},{"name5",5,5.0}};

Next, your current code: char nam[50]; creates a single uninitialized char array, sufficient for containing only 1 string with up to 49 characters, with a terminating \0. If you can, create it like this. (for the sake of learning to copy strings in a loop.)

char nam[5][50] = {{0}};//created 5 elements of null terminated char array elements,

Then you can do this in your loop:

for(i=0;i<n;i++)
{
   strcpy(nam[i], s1[i]name);
}

By now (from comments and answers) you should already know that strings cannot be copied using the = operator like integers or floating numbers. String functions such as strcpy(), or sprintf() can be used to populate strings.

score 0 · Answer 3 · edited Jan 13 '22 at 08:44

0

Use strcpy() I have tried and it's working

edited Jan 13 '22 at 08:44

Peter Csala

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answered Jan 13 '22 at 04:33

Richard S

1

Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Jan 13 '22 at 08:44

how to I copy structure char variable into another char array

3 Answers3