void型で配列の先頭アドレスを受け取り，その配列に波形データを格納する関数

q11210332221.c

/**
 * @file        q11210332221.c
 * @brief       サンプルプログラム
 * @author      Keitetsu
 * @date        2019/07/12
 * @copyright   Copyright (c) 2019 Keitetsu
 * @par         License
 *              This software is released under the MIT License.
 */

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


#define N_DATA      (720)   /**< Number of data */


size_t set_wave_data(void *array, size_t array_size);


int main(int argc, char *argv[])
{
    double *array;
    size_t array_size;
    size_t ret_val;
    FILE *fp;
    size_t t;

    array_size = sizeof(double) * N_DATA;
    array = (double *)malloc(array_size);
    if (array == NULL) {
        fprintf(stderr, "[ERROR] Failed to allocate memory.\n");
        return 1;
    }

    ret_val = set_wave_data(array, array_size);

    fp = fopen("wave_data.csv", "w");
    if (fp == NULL) {
        fprintf(stderr, "[ERROR] Failed to open the file.\n");
        free(array);
        return 2;
    }

    for (t = 0; t < ret_val; t++) {
        fprintf(fp, "%zu, %lf\n", t, array[t]);
    }

    fclose(fp);

    free(array);

    return 0;
}


size_t set_wave_data(void *array, size_t array_size)
{
    size_t n_data;
    size_t t;

    n_data = array_size / sizeof(double);

    for (t = 0; t < n_data; t++) {
        ((double *)array)[t] = sin(t * M_PI / 180.0);
    }

    return t;
}