Array of Pointer to Struct - c

Question

I am a noob to C.I wrote a program that my array people is now an array of pointers to structs. And insert to call malloc to create a new struct and set the correct array element pointing to it.
HERE IS my code.
#include <stdio.h>
/* these arrays are just used to give the parameters to 'insert',
to create the 'people' array
*/
#define HOW_MANY 7 char *names[HOW_MANY]= {"Simon", "Suzie", "Alfred", "Chip", "John", "Tim","Harriet"};
int ages[HOW_MANY]= {22, 24, 106, 6, 18, 32, 24};
/* declare your struct for a person here */
typedef struct{
char* name;
int age;
} person;
static void insert( person *people[], char *name, int age,int i) {
/* put name and age into the next free place in the array parameter
here */
people[i] = malloc(sizeof(person));
people[i]->name = name;
people[i]->age = age;
/* modify nextfreeplace here */
}
int main(int argc, char **argv) {
/* declare the people array here */
person *people[7];
for (int index=0;index < HOW_MANY;index=index+1) {
insert (&people[index], names[index], ages[index],index);
}
/* print the people array here*/
for(int index=0;index < HOW_MANY;index=index+1) {
printf("name: %s, age: %i\n",
people[index]->name, people[index]->age);
}
return 0;
}
And I get errors
part2.c:23:5: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration]
people[i] = malloc(sizeof(person));
^ part2.c:23:17: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default]
people[i] = malloc(sizeof(person));
Can anyone help me? appreciate

Answer 1

I have observed a few issues which are causing these problems. Check the code which I have given below.
There in the comments, I have mentioned where to make changes.
You are using the malloc function without including the stdlib file!
See this code, I have tested it in dev-cpp and it's now working.
#include <stdio.h>
#include <stdlib.h>
/* these arrays are just used to give the parameters to 'insert',
to create the 'people' array
*/
#define HOW_MANY 7
char *names[HOW_MANY]= {"Simon", "Suzie", "Alfred", "Chip", "John", "Tim","Harriet"};
int ages[HOW_MANY]= {22, 24, 106, 6, 18, 32, 24};
/* declare your struct for a person here */
typedef struct{
char* name;
int age;
} person;
/* declare the people array here */
person *people[7];
person* insert(char *name, int age,int i) {
/* put name and age into the next free place in the array parameter
here */
people[i] = malloc(sizeof(person));
people[i]->name = name;
people[i]->age = age;
/* modify nextfreeplace here */
}
int main(int argc, char **argv) {
int index;
for (index=0;index < HOW_MANY;index=index+1) {
insert(names[index], ages[index],index);
}
/* print the people array here*/
for(index=0;index < HOW_MANY;index=index+1) {
printf("name: %s, age: %i\n",
people[index]->name, people[index]->age);
}
return 0;
}

Answer 2

Please see my answer below and compare with your code where you need modification and also try to understand what my code is doing. If you are not clear with any part of my code please feel free to ask me question.
char *names[HOW_MANY]= {"Simon", "Suzie", "Alfred", "Chip", "John", "Tim","Harriet"};
int ages[HOW_MANY]= {22, 24, 106, 6, 18, 32, 24};
/* declare your struct for a person here */
typedef struct{
char* name;
int age;
} person;
static void insert( person *people[], char *name, int age,int i) {
/* put name and age into the next free place in the array parameter
here */
people[i] = malloc(sizeof(person));
people[i]->name = name;
people[i]->age = age;
/* modify nextfreeplace here */
}
int main(int argc, char **argv) {
/* declare the people array here */
person *people[7];
for (int index=0;index < HOW_MANY;index=index+1) {
insert(people, *(names+index), ages[index],index);
}
/* print the people array here*/
for(int index=0;index < HOW_MANY;index=index+1) {
printf("name: %s, age: %i\n",
people[index]->name, people[index]->age);
}
return 0;
}