Comment Removal in C

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

int main()
{
    char *program = 0, *modified_program = 0;
    int file_length = 0, i = 0, j = 0;
    bool s_cmt = false;
    bool m_cmt = false;


    FILE *fp = fopen("input.c", "r");
    FILE *fp2 = fopen("output.c", "w");

    if (!fp)
    {
        printf("Source can't be opened");
        exit(-1);
    }

    fseek(fp, 0, SEEK_END);
    file_length = ftell(fp);
    fseek(fp, 0, SEEK_SET);

    program = (char *)malloc(file_length + 1);
    modified_program = (char *)malloc(file_length + 1);
    fread(program, sizeof(char), file_length, fp);
    program[file_length] = '\0';

    printf("Before removing comment:\n");
    for (i = 0; i < file_length; i++)
    {
        printf("%c", program[i]);
    }

    for (int i = 0; i < file_length; i++)
    {
        if (program[i] == '/' && program[i + 1] == '/')
        {
            s_cmt = true;
            i++;
        }

        else if (program[i] == '/' && program[i + 1] == '*')
        {
            m_cmt = true;
            i++;
        }

        else if (s_cmt == true && program[i] == '\n')
        {
            s_cmt = false;
        }
        else if (m_cmt == true && program[i] == '*' && program[i + 1] == '/')
        {
            m_cmt = false;
            i++;
        }
        else if (s_cmt || m_cmt)
            continue;
        else
        {
            modified_program[j] = program[i];
            j++;
        }
    }
    modified_program[j] = '\0';

    fputs(modified_program, fp2);
    printf("\n\n\n\nAfter removing comment:\n");
    fputs(modified_program, stdout);

    fclose(fp);

    return 0;
}