How to create a struct in C

problem

You wish to represent a custom data type in your C program. In this post we will see how to represent a student object. A student is made of few pieces of information like a name, surname, age, etc.

SOLUTION

In C, we can use struct keyword to create a custom structure of data which acts as a data type.

				
					struct student {
	char name[25];
	char surname[25];
	int age;
};

Above, we just created a new struct to represent a student in our program that will have 3 fields:

name
surname
age

Now, let’s add it to a main program and initialize a student.

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

struct student {
	char name[25];
	char surname[25];
	int age;
};


int main() {
	struct student joe;

    //assign values
	strcpy(joe.name, "Joe");
	strcpy(joe.surname,"Doe");
	joe.age	= 18;
    
    //print values
    printf("%s, %s, %d\n", joe.surname, joe.name, joe.age);

	return 0;
}

At line 12, we declare a new variable of data type (struct student) and then we initialize each field with a value.

Note here that the name and surname are not assignable so we need to use the strcpy function to assign them string values.

At line 20 we can simply print each field by retrieving it using the dot notation.

compiling

In this example, I will compile it using the gcc in the terminal:

				
					gcc student_struct.c

running

				
					./a.out

This is the output in Linux, Mac operating systems, in Windows should be the .exe file. You can refer to their documentation.

output

It prints the joe object as expected.

conclusion

In this post we saw how we can create a data type of our favor, in particular a student that has a name, surname and age. It can easily be extended and have an email, telephone number, gpa. We also saw how to use the dot notation and assign values and also retrieve them for printing.

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Ellion

Professional IT consultant, writer, programmer enthusiast interested in all sorts of coding.
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