‘struct hostent’ has no member named ‘h_addr’
时间: 2024-02-04 17:01:42 浏览: 31
这个错误通常是因为程序使用了过时的函数或结构体。在旧版本的网络编程中,使用`h_addr`来表示主机的IP地址。但是在新版本中,`h_addr`已经被废弃,应该使用`h_addr_list`和`inet_ntoa()`函数来代替。你可以尝试将程序中所有使用`h_addr`的地方替换为`h_addr_list`和`inet_ntoa()`函数来修复这个错误。例如:
```c
struct hostent *hostinfo;
char **addr_list;
char ip[16];
hostinfo = gethostbyname(hostname);
if (hostinfo == NULL) {
printf("gethostbyname failed\n");
return -1;
}
addr_list = (char **)hostinfo->h_addr_list;
for (int i = 0; addr_list[i] != NULL; i++) {
strcpy(ip, inet_ntoa(*(struct in_addr *)addr_list[i]));
printf("IP address: %s\n", ip);
}
```
相关问题
has no member named ‘__getMD5Sum’
As an AI language model, I cannot determine the exact context in which you encountered this error. However, in general, this error message indicates that the code is trying to access a member function or variable called '__getMD5Sum' in a class or struct that does not have such a member. This can happen if there is a typo in the member name, or if the member was not properly defined or declared in the class or struct.
To fix this error, you need to ensure that the member function or variable '__getMD5Sum' is properly defined and declared in the class or struct. Check for any typos or syntax errors in the member name, and make sure that it is declared as public or protected if it needs to be accessed outside of the class or struct. If you are still having trouble, you may need to provide more information or context for me to assist you further.
'struct jpeg_compress_struct' has no member named 'image_quality'
对不起,我之前提供的代码中有一处错误。在libjpeg库中,`struct jpeg_compress_struct`确实没有名为`image_quality`的成员。正确的代码应该是使用`struct jpeg_compress_struct`的`jpeg_set_quality`函数来设置图像的压缩质量。请使用以下修正后的代码:
```c
void compress_image(const char* input_image, const char* output_image, int quality) {
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
FILE* infile, *outfile;
JSAMPROW row_pointer[1];
int row_stride;
if ((infile = fopen(input_image, "rb")) == NULL) {
fprintf(stderr, "Can't open %s\n", input_image);
return;
}
if ((outfile = fopen(output_image, "wb")) == NULL) {
fprintf(stderr, "Can't create %s\n", output_image);
fclose(infile);
return;
}
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_compress(&cinfo);
jpeg_stdio_dest(&cinfo, outfile);
jpeg_read_header(&cinfo, TRUE);
jpeg_set_quality(&cinfo, quality, TRUE); // 设置压缩质量
jpeg_start_compress(&cinfo, TRUE);
row_stride = cinfo.image_width * cinfo.input_components;
unsigned char* buffer = (unsigned char*)malloc(row_stride);
while (cinfo.next_scanline < cinfo.image_height) {
row_pointer[0] = &buffer[cinfo.next_scanline * row_stride];
jpeg_write_scanlines(&cinfo, row_pointer, 1);
}
free(buffer);
jpeg_finish_compress(&cinfo);
fclose(outfile);
jpeg_destroy_compress(&cinfo);
fclose(infile);
}
```
在修正后的代码中,我使用了`jpeg_set_quality`函数来设置压缩质量。你可以传递一个介于0和100之间的整数值作为`quality`参数,其中0表示最低质量,100表示最高质量。
非常抱歉给你带来困扰,希望这次修正后的代码能够帮助到你。如果还有其他问题,请随时提问。