updating string array inside a function in C - c

Question

I define a string array in main function, and I want to update it inside another function as follows:
#include <stdio.h>
#define SIZE 15
void read_arrays(char *competitors[SIZE], float points[SIZE], int numOfCompetitors)
{
for (int cntr = 0; cntr < numOfCompetitors; cntr++)
{
printf("Enter the name of competitor %d", cntr+1);
scanf("%s", &*competitors[cntr]);
printf("Enter the point of competitor %d", cntr+1);
scanf("%f", &points[cntr]);
}
}
int main()
{
char *competitors[SIZE];
float points[SIZE];
int numOfCompetitors = 0;
while (numOfCompetitors > 15 || numOfCompetitors < 1)
{
printf("Enter the number of competitors: ");
scanf("%d", &numOfCompetitors);
if (numOfCompetitors > 15) printf("Number of competitors cannot be more than 15!\n");
}
read_arrays(&*competitors[SIZE], &points[SIZE], numOfCompetitors);
printf("%f", points[0]);
}
But I get the following error:
cc homework2.c -o homework2
homework2.c: In function ‘main’:
homework2.c:28:14: warning: passing argument 1 of ‘read_arrays’ from incompatible pointer type [-Wincompatible-pointer-types]
read_arrays(&*competitors[SIZE], &points[SIZE], numOfCompetitors);
^
homework2.c:5:6: note: expected ‘char **’ but argument is of type ‘char *’
void read_arrays(char *competitors[SIZE], float points[SIZE], int numOfCompetitors)
I want to assign the values in array of strings with scanf in a loop. How I can manage to do that?

Answer 1

You can just use the name of the variable when you pass it to the function, you also need to specify the size of the char matrix (~ array of strings).
So this: read_arrays(&*competitors[SIZE], &points[SIZE], numOfCompetitors);
Becomes: read_arrays(competitors, points, numOfCompetitors);
Full code:
#include <stdio.h>
#define SIZE 15
void read_arrays(char competitors[SIZE][30], float points[SIZE], int numOfCompetitors)
{
for (int cntr = 0; cntr < numOfCompetitors; cntr++)
{
printf("Enter the name of competitor %d", cntr+1);
// We read up to 29 characters => no overflow as the size is up to 30
scanf("%29s", competitors[cntr]);
printf("Enter the point of competitor %d", cntr+1);
scanf("%f", &points[cntr]);
}
}
int main()
{
char competitors[SIZE][30];
float points[SIZE];
int numOfCompetitors = 0;
while (numOfCompetitors > 15 || numOfCompetitors < 1)
{
printf("Enter the number of competitors: ");
scanf("%d", &numOfCompetitors);
if (numOfCompetitors > 15) printf("Number of competitors cannot be more than 15!\n");
}
read_arrays(competitors, points, numOfCompetitors);
printf("%s", competitors[0]);
printf("%s", competitors[1]);
printf("%f", points[0]);
}

Answer 2

As an alternative to Daniel Illescas you could just allocate space for each competitor that you input. Just be sure to free them later.
#include <stdio.h>
#define SIZE 15
void read_arrays(char *competitors[SIZE], float points[SIZE], int numOfCompetitors)
{
for (int cntr = 0; cntr < numOfCompetitors; cntr++)
{
competitors[cntr] = (char*)calloc(1, 32);
printf("Enter the name of competitor %d", cntr + 1);
scanf("%s", competitors[cntr]);
printf("Enter the point of competitor %d", cntr + 1);
scanf("%f", &points[cntr]);
}
}
int main()
{
char *competitors[SIZE];
float points[SIZE];
int numOfCompetitors = 0;
while (numOfCompetitors > 15 || numOfCompetitors < 1)
{
printf("Enter the number of competitors: ");
scanf("%d", &numOfCompetitors);
if (numOfCompetitors > 15) printf("Number of competitors cannot be more than 15!\n");
}
read_arrays(competitors, points, numOfCompetitors);
printf("%f", points[0]);
}