Julia_

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <locale.h>
#include <iostream>
using namespace std;

struct undo
{
    bool op;
    int i,j;
    undo* prev;
    char s[100000];
};

void menu()
{
    printf("\n");
    printf("1:Добавить текст\n");
    printf("2:Удалить между\n");
    printf("3:Назад\n");
    printf("4:Просмотр\n");
    printf("5:Выход\n");
}

int main()
{
    undo * Stack = NULL;
    setlocale(LC_ALL, "Russian");
    int choice;
    char text[10000] = "";
    do
    {
        menu();
        scanf("%d", &choice);
        system("CLS");
        switch (choice)
        {
        case 1:
        {
            char add[10000];
            rewind(stdin);
            gets_s(add);
            strcat(text, add);
            undo *c = (undo *)malloc(sizeof(undo));
            c->prev = Stack;
            Stack = c;
            Stack->op = true;
            Stack->i = strlen(add);
            printf("DONE\n");
            break;
        }
        case 2:
        {
            undo *c = (undo *)malloc(sizeof(undo));
            c->prev = Stack;
            Stack = c;
            Stack->op = false;
            printf("Введите индексы, между которыми хотите удалить текст\n");
            int m, n;
            scanf("%d%d", &n, &m);
            system("CLS");
            char NEW[10000] = "";
            int id = 0;
            int j = 0;
            for (int i = 0; i < strlen(text); i++)
            {
                if (i < n - 1 || m - 1 < i)
                {
                    NEW[id++] = text[i];
                }
                else
                {
                    Stack->s[j++] = text[i];
                }
            }
            strcpy(text, NEW);
            Stack->i = n;
            Stack->j = m;
            printf("DONE\n");
            break;
        }
        case 3:
        {
            if (!Stack)
            {
                printf("Стек пуст\n");
                break;
            }
            if (Stack->op)
            {
                char NEW[10000] = "";
                int id = 0;
                for (int i = 0; i < strlen(text) - Stack->i; i++)
                {
                    NEW[id++] = text[i];
                }
                strcpy(text, NEW);
                undo*c = Stack;
                Stack = Stack->prev;
                free(c);
            }
            else
            {
                char NEW[10000] = "";
                int id = 0;
                for (int i = 0; i < strlen(text); i++)
                {

                    if (i == Stack->i - 1)
                    {
                        for (int j = 0; j < Stack->j-Stack->i+1; j++)
                            NEW[id++] = Stack->s[j];
                    }
                    NEW[id++] = text[i];
                }
                strcpy(text, NEW);
                undo*c = Stack;
                Stack = Stack->prev;
                free(c);
            }
            printf("DONE\n");

            break;
        }
        case 4:
            printf("%s", text);
            break;
        case 5:
            printf("Bye\n");
            break;

        default:
            printf("Такого пункта нет\n");
            break;
        }
    }while (choice != 5);
}