How to parse QUERY_STRING?
Hello! :-)
How to parse query string like this:
user=john&office=35&location=france
QUERY_STRING can contain not more than three pairs
user=john
office=35
location=france
some importances can be not, like only
location=france
or only
user=john&office=35
...
order can be violated:
office=35&location=france&user=john
Sorry for stupid question but my head cannot to do it! :-)
Think about a map... keys correspond to values.
Read up to the equal sign. The string you read (minus the =) is your key. Now read to the ?, that value you read (minus the ?) is the value.
Assign the value you read to the correct variable based on the key, and it's done. Just repeat the process while there is more stuff to parse.
You have to maintain a map of key value pairs. I could implement it fiarly easy in C++ with <map>.. but I don't think there is any similair such tool with standard C.
Last edited by SilentStrike; 03-24-2002 at 01:19 AM.
But what if
char *text = "office=35&user=john&location=france",
Then your method fails. You have to map the key to the value to this... because the order in which they occur is meaningless.
try this, i work well for me.
#include <stdio.h>
#include <stdlib.h>
// Helper macro to convert two-character hex strings to character value
#define ToHex(Y) (Y>='0'&&Y<='9'?Y-'0':Y-'A'+10)
char InputData[4096];
void getAllParams() {
// Determing if it is a POST or GET method
if( getenv( "REQUEST_METHOD" ) == 0 ) {
printf("No REQUEST_METHOD, must be running in DOS mode");
return;
} else if (strcmp( getenv("REQUEST_METHOD"), "POST") == 0) {
// If POST
char *endptr; // quite useless, but required
char *len1 = getenv("CONTENT_LENGTH");
int contentlength = strtol(len1, &endptr, 10);
fread(InputData , contentlength, 1, stdin);
} else {
// If GET
strcpy(InputData, getenv("QUERY_STRING"));
}
}
void getParam(const char *Name, char *Value) {
char *pos1 = strstr(InputData, Name);
if (pos1) {
pos1 += strlen(Name);
if (*pos1 == '=') { // Make sure there is an '=' where we expect it
pos1++;
while (*pos1 && *pos1 != '&') {
if (*pos1 == '%') { // Convert it to a single ASCII character and store at our Valueination
*Value++ = (char)ToHex(pos1[1]) * 16 + ToHex(pos1[2]);
pos1 += 3;
} else if( *pos1=='+' ) { // If it's a '+', store a space at our Valueination
*Value++ = ' ';
pos1++;
} else {
*Value++ = *pos1++; // Otherwise, just store the character at our Valueination
}
}
*Value++ = '\0';
return;
}
}
strcpy(Value, "undefine"); // If param not found, then use default parameter
return;
}
int main() {
char myName[100] = "";
char myAddress[100] = "";
printf("Content-Type:text/html \n\n");
getAllParams();
getParam("Name", myName);
getParam("Address", myAddress);
printf("QueryString: %s", InputData);
printf("<br>");
printf("Name: %s", myName);
printf("<br>");
printf("Address: %s", myAddress);
return 0;
}
Thanks guys!
