ESP8266 send number in IP address

Question

I want to easily send a number from a phone to my esp8266. I have an app that sends the number in the format IP/number. How can I modify the code to give my the number behind the IP address as an integer?

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
MDNSResponder mdns;
// Replace with your network credentials
const char* ssid = "YOUR_SSID";
const char* password = "YOUR_PASSWORD";
ESP8266WebServer server(80);
String webPage = "";
void setup(void){
 delay(1000);
 Serial.begin(115200);
 WiFi.begin(ssid, password);
 Serial.println("");
 // Wait for connection
 while (WiFi.status() != WL_CONNECTED) {
 delay(500);
 Serial.print(".");
 }
 Serial.println("");
 Serial.print("Connected to ");
 Serial.println(ssid);
 Serial.print("IP address: ");
 Serial.println(WiFi.localIP());
 if (mdns.begin("esp8266", WiFi.localIP())) {
 Serial.println("MDNS responder started");
 }
 server.on("/", [](){
 Serial.println("device connected");
 });
 server.begin();
 Serial.println("HTTP server started");
}
void loop(void){
 server.handleClient();
} 

So it would do something like this for and should be looking through every i between 0 and 200. :

server.on("/"+String(i), [](){
 Serial.println("i");
 });

Answer 1

First of all use the event function server.on with a path that corresponds to your function and use a url like this:

192.0.2.2/recordnumber?num=100

With a url parmeter for your number. Your code might look like this:

At the top:

int nums_size = 0;
const int nums_max = 128;
int nums[nums_max];

In setup:

server.on("/recordnumber", [](){
 int num;
 if(server.hasArg("num")) {
 String num_str = server.arg("num");
 if(num_str.charAt(0) == '0') {
 num = 0;
 } else {
 num = num_str.toInt();
 if(num == 0) {
 server.send(400, "text/plain", "not a number");
 return;
 }
 }
 if(nums_size < nums_max) {
 nums[nums_size++] = num;
 server.send(200, "text/plain", "saved");
 } else {
 server.send(500, "text/plain", "full");
 }
 } else {
 server.send(400, "text/plain", "bad params");
 }
});

Answer 2

First you need to extract the string that contains the number (after the /). Since it is already stored in consecutive memory you can pass the pointer to the character after the / symbol to the C function atoi to convert it to an integer.

I assume the pointer is already 0円 terminated.

You can use the C function strchr to search for the / symbol.

Tip: use a C compiler on a desktop/PC to check how these functions work. Once you know how to use them, copy them in your Arduino code. This is much faster than uploading/debugging sketches probably.

• luukito: My phone accesses the ESP via it's IP address for instance: 192.168.2.2/100 or 192.168.2.2/200. The ESP should than store these values 100 and 200 into integers but these numbers could be any number
• Michel Keijzers: I adapted the answer, use strchr to search for the / symbol, than use atoi
• luukito: But in order to extract the right part of the string how do you store the whole incoming IP address in a string?
• Michel Keijzers: WiFi.localIP() is already pointing to a string, you can use this as input for strchr to search for the / symbol, than you can use atoi.