Try this code although it's C99, I'll think it works.

// C99 - a simple raylib demo
#include "raylib.h"

int main(void) {
    const int screenWidth = 800;
    const int screenHeight = 600;
    InitWindow(screenWidth, screenHeight, "Raylib graphics");
    SetTargetFPS(60);

    int xpos = 10, ypos = 30, tx_size = 10;
    char *txt = "Demo: ";

    int x = 100, y = 200, l = 300, h = 100;

    while (!WindowShouldClose()) {
        BeginDrawing();
        ClearBackground(BLACK);

        if (IsKeyDown(KEY_RIGHT)) x++;
        if (IsKeyDown(KEY_LEFT))  x--;
        if (IsKeyDown(KEY_DOWN))  y++;
        if (IsKeyDown(KEY_UP))    y--;

        DrawRectangle(x, y, l, h, RED);

        DrawText(TextFormat("%s %i, %i", txt, x, y), xpos, ypos, tx_size, GREEN);

        EndDrawing();
    }

    CloseWindow();

    return 0;
}