C语言 读取二进制文件，存入缓冲区，打印出缓冲区内容
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Read binary file, save in buffer, print out content of buffer
提问by user2418126
I have a big problem that need's to be solved before I can continue with my program.
我有一个大问题需要解决，然后才能继续我的程序。
I have to open a binary file, read it's content, save the content into a buffer, allocate space on the heap with malloc, close the file and finally printf( the content of the .bin file). I came this far (closing file is not implemented yet):
我必须打开一个二进制文件，读取它的内容，将内容保存到缓冲区中，使用 malloc 在堆上分配空间，关闭文件，最后 printf（.bin 文件的内容）。我走到这一步（关闭文件尚未实现）：
void executeFile(char *path){
FILE *fp; /*filepointer*/
size_t size; /*filesize*/
unsigned int buffer []; /*buffer*/
fp = fopen(path,"rb"); /*open file*/
fseek(fp, 0, SEEK_END);
size = ftell(fp); /*calc the size needed*/
fseek(fp, 0, SEEK_SET);
buffer = malloc(size); /*allocalte space on heap*/
if (fp == NULL){ /*ERROR detection if file == empty*/
printf("Error: There was an Error reading the file %s \n", path);
exit(1);
}
else if (fread(&buffer, sizeof(unsigned int), size, fp) != size){ /* if count of read bytes != calculated size of .bin file -> ERROR*/
printf("Error: There was an Error reading the file %s - %d\n", path, r);
exit(1);
}else{int i;
for(i=0; i<size;i++){
printf("%x", buffer[i]);
}
}
}
I think I messed up the buffer and I am not really sure if I read the .bin file correctly because I can't print it with printf("%x", buffer[i])
我想我弄乱了缓冲区，我不确定我是否正确读取了 .bin 文件，因为我无法打印它 printf("%x", buffer[i])
Hope you guys can help
希望大家帮帮忙
Greetings from germany :)
来自德国的问候 ：）
回答by chux - Reinstate Monica
Recommended changes:
建议更改：
1) Change your buffer to a char(byte), as the ftell()will report the size in bytes (char) and malloc()use the byte size also.
1) 将缓冲区更改为char(byte)，因为它ftell()会以字节 ( char)为单位报告大小并也malloc()使用字节大小。
unsigned int buffer []; /*buffer*/
to
到
unsigned char *buffer; /*buffer*/
2) This is OK, size is bytes and buffer points to bytes, but could be explicitly cast
2) 这没问题，大小是字节，缓冲区指向字节，但可以显式转换
buffer = malloc(size); /*allocate space on heap*/
to
到
buffer = (unsigned char *) malloc(size); /*allocate space on heap*/
/* or for those who recommend no casting on malloc() */
buffer = malloc(size); /*allocate space on heap*/
3) change 2nd parameter from sizeof(unsigned int)to sizeof *buffer, which is 1.
3) 将第二个参数从sizeof(unsigned int)改为sizeof *buffer，即 1。
else if (fread(buffer, sizeof(unsigned int), size, fp) != size){
to
到
else if (fread(buffer, sizeof *buffer, size, fp) != size){
4) Change "%x"to "%02x"else single digit hexadecimal numbers will confuse the output. E. g. is "1234" four bytes or two?
4) 更改"%x"为"%02x"else 一位十六进制数字会混淆输出。例如 “1234”是四个字节还是两个字节？
printf("%x", buffer[i]);
to
到
printf("%02x", buffer[i]);
5) Your clean-up at the end of the function may include
5) 您在函数结束时的清理可能包括
fclose(fp);
free(buffer);
