要求用c语言实现一个笔记管理系统，要求有基于libgraphics/ simpleGUI 图形库实现的界面，要求编写代码

好的，笔记管理系统的功能包括新建笔记、编辑笔记、删除笔记、查看笔记等。需要用到文件操作和图形界面库。

以下是一个简单的实现：

#include <stdio.h>
#include <graphics.h>
#include <conio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_NOTE_NUM 100
#define MAX_NOTE_LENGTH 1000

struct note {
    char title[50];
    char content[MAX_NOTE_LENGTH];
};

struct note notes[MAX_NOTE_NUM];
int note_num = 0;

void draw_main_window();
void draw_note_list();
void draw_note_editor(int note_id);
void save_notes();
void load_notes();

int main() {
    initwindow(800, 600, "Note Manager");

    load_notes();

    while (1) {
        draw_main_window();
        draw_note_list();

        if (ismouseclick(WM_LBUTTONDOWN)) {
            int x = mousex();
            int y = mousey();

            if (x > 10 && x < 110 && y > 50 && y < 80) { // new note button
                note_num++;
                strcpy(notes[note_num - 1].title, "Untitled");
                strcpy(notes[note_num - 1].content, "");
                draw_note_list();
                draw_note_editor(note_num - 1);
            } else if (x > 10 && x < 110 && y > 90 && y < 120) { // save button
                save_notes();
            } else {
                for (int i = 0; i < note_num; i++) {
                    if (x > 130 && x < 330 && y > 50 + i * 40 && y < 90 + i * 40) { // note item
                        draw_note_editor(i);
                        break;
                    }
                }
            }
        }

        delay(50);
    }

    return 0;
}

void draw_main_window() {
    setcolor(WHITE);
    settextstyle(BOLD_FONT, HORIZ_DIR, 24);
    outtextxy(10, 10, "Note Manager");

    settextstyle(BOLD_FONT, HORIZ_DIR, 16);
    outtextxy(10, 50, "New Note");
    outtextxy(10, 90, "Save");
}

void draw_note_list() {
    cleardevice();
    draw_main_window();

    settextstyle(BOLD_FONT, HORIZ_DIR, 18);
    for (int i = 0; i < note_num; i++) {
        outtextxy(130, 50 + i * 40, notes[i].title);
    }
}

void draw_note_editor(int note_id) {
    cleardevice();

    settextstyle(BOLD_FONT, HORIZ_DIR, 16);
    outtextxy(10, 10, "Title:");
    outtextxy(10, 50, "Content:");

    settextstyle(BOLD_FONT, HORIZ_DIR, 18);
    outtextxy(130, 10, notes[note_id].title);

    char temp_content[MAX_NOTE_LENGTH];
    strcpy(temp_content, notes[note_id].content);
    char* content_ptr = strtok(temp_content, "\n");
    int line_num = 0;
    while (content_ptr != NULL) {
        outtextxy(130, 50 + line_num * 30, content_ptr);
        content_ptr = strtok(NULL, "\n");
        line_num++;
    }

    char c;
    int index = strlen(notes[note_id].content);
    while (1) {
        if (kbhit()) {
            c = getch();
            if (c == 13) { // enter key
                strcat(notes[note_id].content, "\n");
                line_num++;
                outtextxy(130, 50 + (line_num - 1) * 30, "");
            } else if (c == 8 && index > 0) { // backspace key
                index--;
                notes[note_id].content[index] = '\0';
                cleardevice();
                draw_note_editor(note_id);
                break;
            } else if (c >= 32 && c <= 126 && index < MAX_NOTE_LENGTH - 1) {
                notes[note_id].content[index] = c;
                notes[note_id].content[index + 1] = '\0';
                index++;
                outtextxy(130, 50 + (line_num - 1) * 30, notes[note_id].content + strlen(notes[note_id].content) - strlen(content_ptr));
                content_ptr = strtok(NULL, "\n");
                if (content_ptr != NULL) {
                    line_num++;
                }
            }
        }

        if (ismouseclick(WM_LBUTTONDOWN)) {
            int x = mousex();
            int y = mousey();

            if (x > 10 && x < 110 && y > 50 && y < 80) { // delete button
                for (int i = note_id; i < note_num - 1; i++) {
                    notes[i] = notes[i + 1];
                }
                note_num--;
                draw_note_list();
                break;
            } else if (x > 10 && x < 110 && y > 90 && y < 120) { // save button
                save_notes();
                break;
            }
        }

        delay(50);
    }
}

void save_notes() {
    FILE* fp = fopen("notes.txt", "w");
    if (fp == NULL) {
        return;
    }

    fprintf(fp, "%d\n", note_num);
    for (int i = 0; i < note_num; i++) {
        fprintf(fp, "%s\n%s\n", notes[i].title, notes[i].content);
    }

    fclose(fp);
}

void load_notes() {
    FILE* fp = fopen("notes.txt", "r");
    if (fp == NULL) {
        return;
    }

    fscanf(fp, "%d\n", &note_num);
    for (int i = 0; i < note_num; i++) {
        fgets(notes[i].title, 50, fp);
        if (notes[i].title[strlen(notes[i].title) - 1] == '\n') {
            notes[i].title[strlen(notes[i].title) - 1] = '\0';
        }
        fgets(notes[i].content, MAX_NOTE_LENGTH, fp);
        if (notes[i].content[strlen(notes[i].content) - 1] == '\n') {
            notes[i].content[strlen(notes[i].content) - 1] = '\0';
        }
    }

    fclose(fp);
}

以上代码仅供参考，可能还需要优化和改进。