How to get a file name in C - c

Question

I am trying to get a file name in C, at my project I will have three files, like Randomic%08d.txt, Inverted%08d.txt and Ordered%08d.txt, where this %08d represents the range I typed, if I typed range equal 3, the file name will be Randomic00000003.txt. I thought to get a file name just returning the file name at the functions in generateFiles.h but I guess that is not good to do because I will have change the return function type.
I want to get the file name because I will need to define a vector with the file data so I need to open the file.
main.c
#include <stdio.h>
#include "generateFiles.h"
int main(void) {
FILE *ordered, *inverted, *randomic;
int range, choice;
char fileName[255];
do {
printf("Menu\n\n");
printf("1 - Criar arquivos \n");
printf("2 - Ordenar usando Bubble Sort \n");
printf("3 - Ordenar usando Insertion Sort \n");
printf("4 - Fechar programa \n");
scanf("%d", &choice);
switch(choice) {
case 1:
printf("Informe o tamanho do arquivo: ");
scanf("%d", &range);
createOrderedFile(range, fileName, ordered);
createInvertedFile(range, fileName, inverted);
createRandomicFile(range, fileName, randomic);
break;
case 2:
fopen("Randomic%08d.txt", "r");
break;
}
} while(choice != 4);
}
generateFiles.h
#include <stdlib.h>
int INDEX = 0;
void createOrderedFile(int range, char fileName[255], FILE *ordered) {
int index;
sprintf(fileName, "Ordered%08d.txt", range);
ordered = fopen(fileName, "w");
for (INDEX = 1; INDEX <= range; INDEX++) {
fprintf(ordered, "%d\n", INDEX);
}
fclose(ordered);
}
void createInvertedFile(int range, char fileName[255], FILE *inverted) {
sprintf(fileName, "Inverted%08d.txt", range);
inverted = fopen(fileName, "w");
for (INDEX = range; INDEX >= 1; INDEX--) {
fprintf(inverted, "%d\n", INDEX);
}
fclose(inverted);
}
void createRandomicFile(int range, char fileName[255], FILE *randomic) {
sprintf(fileName, "Randomic%08d.txt", range);
randomic = fopen(fileName, "w");
for (INDEX = 1; INDEX <= range; INDEX++) {
fprintf(randomic, "%d\n", rand() % range + 1);
}
fclose(randomic);
}