`struct` in C¶

Structure also called struct is a data type in C are a way to group several related variables into one place.

Each variable in the structure is known as a member of the structure.
Unlike an array, a structure can contain many different data types (int, float, char, etc.).

Create a Structure¶

    struct  StudentInfo {        // Structure declaration
        char[] name;      // Member (char variable)
        int id;             // Member (int variable)
    }

To access the structure, you must create a variable of it.

struct  StudentInfo {
    char name[20];
    int id;
};

int main () {
    struct StudentInfo s1 = {"Rakib", 003};
    struct StudentInfo s2 = {"Jawad", 010};

    return 0;
}

মনে রাখতে হবেঃ

struct decalaration এর পরে কিন্তু অবশ্যই এটার শেষে semi-colon ; দিতে হবে। কারণ এটা অনেকটা একটা variable এর মতোই। তাই close করতে হবে।

Access Structure Members¶

To access structure members we use dot (.) syntax.

What About Strings in Structures?¶

Remember that strings in C are actually an array of characters, and unfortunately, you can't assign a value to an array like this:

However, there is a solution for this! You can use the strcpy() function and assign the value to s3.StudentInfo, like this:

CodeResults

// Online C compiler to run C program online
#include <stdio.h>
#include <string.h>

struct StudentInfo {
char name[20];
int id;
};

    int main () {

    // we can assign value inline
    struct StudentInfo s1 = {"Rakib", 3};
    struct StudentInfo s2 = {"Jawad", 10};

    // or we can use dot  systax for assigning or accessig the value:
    struct StudentInfo s3;
    strcpy(s3.name, "Tuku");
    s3.id =20;

    printf("%d\n", s1.id);
    printf("%s\n", s1.name);
    printf("%s\n", s2.name);
    printf("%s", s3.name);
    return 0;
}

Simpler Syntax¶

You can also assign values to members of a structure variable at declaration time, in a single line.

Just insert the values in a comma-separated list inside curly braces {}. Note that you don't have to use the strcpy() function for string values with this technique:

Copy Structures¶

You can also assign one structure to another. In the following example, the values of s1 are copied to s2:

struct StudentInfo {
char name[20];
int id;
};

    int main () {

    // we can assign value inline
    struct StudentInfo s1 = {"Rakib", 3};
    struct StudentInfo s2 = {"Jawad", 10};

    s1=s2;

    return 0;
}

Garbage value printing:¶

If we want to directly print a structure variable directly, the first problem we face is that we don't have any format specifier for that like: %d, %f, %s etc. Even though, if we try prining the structure with one of these format specifiers, then we see garbage values.

CodeResult

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

struct StudentInfo {
char name[20];
int id;
};

    int main () {

    // we can assign value inline
    struct StudentInfo s1 = {"Rakib", 3};
    struct StudentInfo s2 = {"Jawad", 10};

    struct StudentInfo s3;
    strcpy(s3.name, "Tuku");
    s3.id =20;

    printf("%s", s3);
    printf("%d", s3);

    printf()
    return 0;
}

struct in C¶