c语言之IO使用文件分割

#include <stdio.h>#include <math.h>   // ceil()#include <stdlib.h> // exit()//cl filesplit.cint main(int argc, char *argv[]) {    char part_filename[200];    FILE *ptr_source, *ptr_part;    size_t parts, i;    unsigned long int part_size, written_bytes;    int byte;    if (argc != 3) {        printf("Usage: %s <maximum part_size in MB> <file to split>\n", argv[0]);        exit(1);    }    if ((ptr_source = fopen(argv[2], "rb")) == NULL) {        perror("Could not open file to split");        exit(1);    }    fseek(ptr_source, 0, SEEK_END);    part_size = atol(argv[1]) * 1024 * 1024;    if (part_size == 0) {        printf("Invalid part size: %s\n", argv[1]);        exit(1);    }    parts = (size_t) ceil((double) ftell(ptr_source) / part_size);    rewind(ptr_source);    printf("File will be split into %u parts.\n", parts);    for (i = 0; i < parts; i++) {        printf("\nWriting part%02d... ", i);        sprintf(part_filename, "%s.part%02d", argv[2], i);        if ((ptr_part = fopen(part_filename, "wb")) == NULL) {            perror("Could not open part for writing");            exit(1);        }        for (written_bytes = 0; written_bytes < part_size &&            (byte = fgetc(ptr_source)) != EOF; written_bytes++)        {            fputc(byte, ptr_part);        }        printf("(%lu bytes)", written_bytes);        fclose(ptr_part);    }    printf("\n\nDone!\n");    fclose(ptr_source);    return 0;}