Step 1 of 7

Define a struct

Real data comes in groups. A player has a name, kills and deaths; a point has an x and a y. Keeping them in separate variables means passing three arguments everywhere and hoping they stay in sync. A struct bundles related variables into one new type.

#include <stdio.h>

struct Book {
    const char *title;
    int year;
    double price;
};

int main(void) {
    struct Book b = {"The C Programming Language", 1978, 45.0};
    printf("%s (%d)\n", b.title, b.year);
    b.price = b.price * 0.8;
    printf("sale price %.2f\n", b.price);
    return 0;
}

The C Programming Language (1978)
sale price 36.00

The parts

• struct Book { ... }; defines the type: a blueprint listing the members (also called fields). Note the semicolon after the closing brace; forgetting it gives a confusing error on the next line.
• struct Book b creates a variable of that type. The type's full name includes the word struct.
• {"...", 1978, 45.0} initializes the members in the order they're declared. You can also name them: {.year = 1978, .title = "...", .price = 45.0}, which is clearer and survives reordering.
• b.title uses the dot operator to reach one member. Each member is a normal variable you can read and assign.

In memory

A struct's members are stored together, in declaration order, as one block. The compiler may add a few bytes of padding between members so each is aligned for fast access, which is why sizeof(struct Book) can be larger than the sum of its members.

Your task

Complete the struct and print the weapon's name and damage.

Challenge 2

Give the point the coordinates 3 and 4, then move it 10 to the right by changing only its x field. The output is 13 4.

Challenge 3

Define a struct Round with two int fields, number and kills. Create two rounds, round 1 with 3 kills and round 2 with 5 kills, and print:

round 1: 3 kills
round 2: 5 kills
total 8

Compute the total from the two structs.

Next: Structs in functions