【发布时间】：2013-02-06 02:22:17
【问题描述】：
我是一名编程初学者，我的大学有一项任务是编写 C 代码，用于读取 ID3V2 格式的 mp3 文件。我已经在网上搜索并尝试将一些部分放在一起，然后我想出了这段代码。尽管我从上到下放置了许多错误警告，但我仍然无法理解错误在哪里。
我的第一个问题是它编译的代码只有一个警告： 警告：格式“%s”需要匹配的“char *”参数 [-Wformat]
不幸的是，我不知道我的错误是什么。我正在尝试打印用户的输入以防出现错误，我认为这样做会收到此警告。
我的第二个问题是当我执行作为输出得到的代码时： 程序获取标签失败
任何帮助将不胜感激。
提前感谢您抽出宝贵时间阅读我的问题。
最好的问候， 灭霸
这是我目前的代码：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct{
char tag[3];
char title[30];
char artist[30];
char album[30];
char year[4];
char comment[30];
unsigned char genre;
}mp3Info;
int main (int argc, char *argv[])
{
if ( argc != 1 ) /* Input from user argc should be 1 for correct
*execution. The argument count variable
* stores the number of arguments plus one. */
{
/*We print argv[0], if the program that user has chosen for
* execution it is not correct as input if has more inputs*/
printf( "Please choose one file: %s <silence.mp3> \n", argv[0] );
}
else
{
FILE *file; /* A file pointer is a variable of type FILE,
* we declare a file pointer.*/
file = fopen("silence.mp3", "rb"); /* Open the file
* silence.mp3 in
* "reading" mode "r". */
if (file == NULL) {
/* If the file could not open for a variety of reasons
* the program should inform us by print the document
* and exit.*/
printf("I couldn't open: %s for reading.\n");
exit(0);
}
else
{
mp3Info tag_in;
/* Set the fseek to the beggining of the document with
* the help of the command SEEK_SET, condition if fail*/
if (fseek(file, 0 *sizeof(mp3Info), SEEK_SET) == -1)
{
fprintf(stderr, "Not able to fseek");
return EXIT_FAILURE;
}
/* Read the first name "tag" */
if (fread(&tag_in, sizeof(mp3Info), 1, file) != 1)
{
printf("Could not read the tag\n");
exit (0);
}
/* Compare memory areas for verification */
if (memcmp(tag_in.tag, "TAG", 3) == 0)
{
/* Verify that names are where as we expect */
printf("Title: %.30s\n", tag_in.title);
printf("Artist: %.30s\n", tag_in.artist);
printf("Album: %.30s\n", tag_in.album);
printf("Year: %.4s\n", tag_in.year);
if (tag_in.comment[28] == '\0')
{
printf("Comment: %.28s\n", tag_in.comment);
printf("Track: %d\n", tag_in.comment[29]);
}
else
{
printf("Comment: %.30s\n", tag_in.comment);
}
printf("Genre: %d\n", tag_in.genre);
}
else
{
fprintf(stderr, "The program has failed to get the Tags\n");
return EXIT_FAILURE;
}
fclose(file);
return 0;
}
}
}
【问题讨论】：
-
您将 ID3v1 与 ID3v2 格式混淆了。