问题描述
我有这个超级简单的代码,我在其中读取8个字节的块(稍后将在代码中对其进行加密),然后将它们写到一个新文件中.
I have this super simple code where I read blocks of 8 bytes (I will encrypt them later in the code) and then write them down in a new file.
它工作得很好,但对于最后8个字节没有写入.知道为什么吗?
It works well but for the last 8 bytes which don't get written. Any idea why?
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
int main()
{
uint64_t data;
FILE *input, *output;
// create output file
output = fopen("output.txt", "w");
// read file
input = fopen("test.txt", "rb");
if(input)
{
while(fread(&data, 8, 1, input) == 1)
{
fwrite(&data, 8, 1, output);
}
size_t amount;
while((amount = fread(&data, 1, 8, input)) > 0)
{
fwrite(&data, 1, amount, output);
}
fclose(input);
fclose(output);
}
return EXIT_SUCCESS;
}
推荐答案
fread(&data, 8, 1, input)
尝试将一个8字节的项目"读入缓冲区,并返回项目数.如果从当前位置到EOF剩余少于8个字节,则返回0.
tries to read one "item" with 8 bytes into the buffer, and returns the number of items.If less than 8 bytes are left from the current position to EOF, it returns 0.
一种可能的解决方案是改为读取8个项目à1个字节:
One possible solution would be to read 8 items à 1 byte instead:
ssize_t amount;
while ((amount = fread(&data, 1, 8, input)) > 0)
{
fwrite(&data, 1, amount, output);
}
然后在while块中,您可以检查amount
是否为8或更小加密方法.
Inside the while-block you can then check if amount
is 8 or less, for yourencryption method.
这篇关于用C语言读写64位乘64位的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!