Compile a program containing the following code:
if (cmd == -1)
{
plen=fill_tcp_data_p(buf,0,PSTR("HTTP/1.0 401 Unauthorized\r\nContent-Type: text/html\r\n\r\n
401 Unauthorized
"));goto SENDTCP;
}
The compilation result gives the following warning for this line:
web_server.c(288): warning: #514-D: pointless comparison of unsigned integer with a negative constant.
The general meaning is: a meaningless comparison between an unsigned integer and a negative constant
. Find the cause: The cmd variable is defined as:
unsigned char cmd;
the solution is as follows:
if (cmd == (unsigned char)-1)
{
plen=fill_tcp_data_p(buf,0,PSTR("HTTP/1.0 401 Unauthorized\r\nContent-Type: text/html\r\n\r\n
401 Unauthorized
"));goto SENDTCP;
}
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