使用 fread 和 fwrite 复制二进制文件

Question

我在使用 fread 和 fwrite 复制二进制文件时遇到问题:循环仅运行两次(40 字节)，但文件长度为 160 字节:

#include <string.h>
#define PER_READ 30
int main(void)
{

    char buffer[500] = { 0 };
    FILE* CSV = fopen( "CSV.csv", "rb" );
    FILE* csvDest = fopen( "CSVDest.csv", "wb" );
    unsigned int finished = 0;
    unsigned int counter = 0;
    do
    {
        finished = fread( buffer, sizeof( char*), PER_READ, CSV );//Read all from CSV to a string name buffer
        finished += PER_READ * counter;
        counter++;
    } while (finished == PER_READ * counter);
    fwrite( buffer, sizeof( char* ), finished, csvDest );// write all to a the file CSVDest

    system( "PAUSE" );
    return (0);
};

Answer 1

您的实现可以是像这样的简单循环，它会重复直到没有读取任何字节。请注意，sizeof(char*) 是错误的 - 指针的大小，而 sizeof(char) 根据定义是 1。

#include <stdio.h>                                              // include proper header

#define BUFFSIZE    512                                         // power of 2 is kind to system

int main(void)
{
    char buffer[BUFFSIZE];
    size_t bytes;
    FILE *fin, *fou;
    fin = fopen("CSV.csv", "rb");
    fou = fopen("CSVDest.csv", "wb");
    if(fin == NULL || fou == NULL)
        return 1;                                               // or other action
    while ((bytes = fread(buffer, 1, BUFFSIZE, fin)) != 0) {
        if(fwrite(buffer, 1, bytes, fou) != bytes) {
            return 1;                                           // or other action
        }
    }
    fclose(fou);
    fclose(fin);
    return 0;
}