sorting - How to sort a group of structures in C -

i made 4 variables structures , assigned values age.

 struct database {  int id_number;  int age;  float salary;  };   main()  {  struct database employee[4];  struct database current; // used later in attempted sorting   employee[1].age = 12;   employee[2].age = 112;   employee[3].age = 2;   employee[4].age = 22; 

i tried various ways attempt sort these failed, example:

 for(i = 0; < 4; i++)  {      current = employee[i];//"current" assigned same type of struct      j = i;       while(employee[j-1].age > current.age)      {         employee[j] = employee[j-1];         j = j-1;      }      employee[j] = current;  } 

many errors, pointed others in comments.

(out of bound array access, sorting algorithm not correct, etc. )

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for sorting array of struct, simplest way use qsort need define custom comparator, following :

typedef struct database db;  int sort_by_age(void *a, void *b) {   db *_a = (db *)a;   db *_b = (db *)b;    if( _a->age > _b->age  ) return -1;   if( _a->age == _b->age ) return 0;    return 1; } 

and use like,

int no_of_employee = 4;  qsort( employee, no_of_employee, sizeof(db), sort_by_age );