/*Write a program that indefinitely takes in files to append to a master
file. If the file names are the same, don't do it. If there's an error,
don't do it. Exit with a blank line. Use a custom buffer.*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_NAME 25
#define BUFSIZE 1024
int append(FILE *, FILE *);
int main(){
char src[MAX_NAME], mainfile[MAX_NAME];
FILE *src_ptr, *mainfile_ptr;
int successes = 0;
puts("Enter name of main file");
if(gets(mainfile) == NULL){
fprintf(stderr, "Error, couldn't get filename\n");
return 1;
}
if((mainfile_ptr = fopen(mainfile, "ab")) == NULL){
fprintf(stderr, "Error, couldn't open mainfile\n");
return 1;
}
do{
puts("Enter a filename to be appended");
if(gets(src) == NULL || src[0] == '\0' || strcmp(src, mainfile) == 0){
if(src[0])
puts("Error, couldn't get filename!");
continue;
}
if((src_ptr =fopen(src, "rb")) == NULL){
puts("Error, could not open file");
continue;
}
if(setvbuf(src_ptr, NULL, _IOFBF, BUFSIZE) != 0){
puts("Couldn't create filebuffer!");
continue;
}
if(append(src_ptr, mainfile_ptr) != 0){
fflush(src_ptr);
puts("Couldn't append!");
continue;
}
fclose(src_ptr);
++successes;
printf("Successfully appended %s, %d files total\n", src, successes);
}while(src[0] != '\0');
fclose(mainfile_ptr);
printf("Successfully appended %d files, bye!\n", successes);
return 0;
}
int append(FILE *src, FILE *mainfile){
size_t bytes = 0;
static char buffer[BUFSIZE];
while(bytes = (fread(buffer, sizeof(char), BUFSIZE, src)) > 0)
fwrite(buffer, sizeof(char), BUFSIZE, mainfile);
if(ferror(src) || ferror(mainfile))
return 1;
return 0;
}
你好。根据C Primer Plus示例,我编写了一个附加内容的程序
用户指定的文件到主文件。最初我写它只打算用它
文本文件,但后来我改变它以二进制模式工作。我用它来附加四个文件。我得到了一些非常奇怪的结果,我不知道为什么。这是完成的截图
文件(我必须截图它,因为它充满了非常奇怪的字符)。我得到了同样的结果
结果没有用fopen在二进制模式下打开它们。它似乎“追加”我的文件
多次,其中一些只有一半,然后是另一半。
我哪里出错了?
我不知道为什么它如此重新调整大小。
答案 0 :(得分:9)
while(bytes = (fread(buffer, sizeof(char), BUFSIZE, src)) > 0)
fwrite(buffer, sizeof(char), BUFSIZE, mainfile);
应该是
while((bytes = fread(buffer, sizeof(char), BUFSIZE, src)) > 0)
fwrite(buffer, sizeof(char), bytes, mainfile);
在fread
返回小于BUFSIZE
字节的情况下,您将先前读取的数据写入mainfile
。
您还可以检查fwrite
是否返回bytes
,选择是否中止或重试写入缓冲区的剩余部分。