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#include <stdio.h>#include <stdlib.h>#include "list.h"#define _GNU_SOURCEint main(){	int option, n, id, i;	student *st = NULL;	char name[64];			while(1)	{		system("clear");		displayMenu();		scanf("%d", &option);				if(option < 9 && option )		{			switch(option)			{				case 0:					puts("");					break;									case 1:					puts("Please insert the number of initial elements:");					scanf("%d", &n);					st = allocStructure(n);					if(st != NULL)					{						puts("Memory succesfully allocated");						getchar();					}					getchar();					break;									case 2:					inputData(n, st);					getchar();					break;									case 3:					outputData(n, st);					getchar();										break;				case 4:					qsort(st, n, sizeof(student), cmpStudent);					puts("Success!");					getchar();					getchar();					break;				case 5:					puts("Type students' name:");					scanf("%s", &name);					searchStudent(st, name, n);					getchar();					getchar();					break;				case 6:					addStudent(st, n);					getchar();					++n;					break;				case 7:					puts("Enter student's id:");					scanf("%d", &id);										deleteStudent(st, id, n);					getchar();					getchar();					--n;					break;				case 8:					if ((file = fopen("student.dat", "w")) == NULL)						fprintf(stderr, "Cannot open %s\n", "output_file");					for(i=0;i<n;i++)					{						fprintf(file, "%s %d %f", st[i].name, st[i].year, st[i].mark);					}					break;									case 9:					if(!st)					{						free(st);						st = NULL;					}					break;				default: 					puts("Invalid option:");					getchar();					getchar();			}		}			}}