Extract Message from Request Path

Task

Implement the function get_message.

• Write a function that extracts the message from a request path
• The path format could be /post?user=<username>&message=<message> or /react?...&message=<message>&id=<id>
• Return an interior pointer to the message within the original string
• You should modify the string by replacing the & after the message with \0 (if there is one)
• If there is no message= parameter, return NULL

Function Signature

// Given a request path, return a pointer to the message (or NULL if not found)
char* get_message(char* request_path);

Note

• Find message= in the string (it could be in /post, /react, or other paths)
• The message starts immediately after message=
• The message ends at the & character (if present) or end of string
• Replace the & with \0 to terminate the message string (if there is one)
• Return a pointer to the start of the message (an interior pointer into the original string)
• If there is no message= in the path, return NULL
• If message= exists but there’s no & after it, you can still return the pointer (it will go to end of string)

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Example

Input	Output
/post?user=joe&message=hi	hi
/react?user=aaron&message=👍&id=5	👍
/post?user=alice&message=hello%20world	hello%20world
/chats	NULL
/post?user=bob	NULL

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Code

#include <stdio.h>
#include <string.h>
 
char *get_message(char *request_path)
{
    char* message = strstr(request_path, "message=");
    if(message != NULL){
        message += 8;
        char* end = strstr(message, "&");
        if(end != NULL){
            *end = 0;
        }
        return message;
    }
    return NULL;
}