String does not name a type

Question

I'm using Arduino IDE for ESP32 WROOM board. I am testing the OTA feature with the ESP32httpUpdate library. I am using the example sketch of the library with the name httpUpdate.ino However, as soon as I change the update url with a string pointer that I declare globally, it is throwing a compile error that String does not name a type. Any ideas?

/**
 * httpUpdate.ino
 *
 * Created on: 27.11.2015
 *
 */
String* FIRMWARE_UPDATE_VERSION = "1000";
String* updateURL = "XYZ.php";
#include <Arduino.h>
#include <WiFi.h>
#include <HTTPClient.h>
#include <ESP32httpUpdate.h>
#define USE_SERIAL Serial
void setup() {
 USE_SERIAL.begin(115200);
 // USE_SERIAL.setDebugOutput(true);
 USE_SERIAL.println();
 USE_SERIAL.println();
 USE_SERIAL.println();
 for(uint8_t t = 4; t > 0; t--) {
 USE_SERIAL.printf("[SETUP] WAIT %d...\n", t);
 USE_SERIAL.flush();
 delay(1000);
 }
 WiFi.begin("SSID", "PASSWORD");
}
void loop() {
 // wait for WiFi connection
 Serial.println("Yolo");
 if((WiFi.status() == WL_CONNECTED)) {
 t_httpUpdate_return ret = ESPhttpUpdate.update(updateURL, FIRMWARE_UPDATE_VERSION);
 switch(ret) {
 case HTTP_UPDATE_FAILED:
 USE_SERIAL.printf("HTTP_UPDATE_FAILD Error (%d): %s", ESPhttpUpdate.getLastError(), ESPhttpUpdate.getLastErrorString().c_str());
 break;
 case HTTP_UPDATE_NO_UPDATES:
 USE_SERIAL.println("HTTP_UPDATE_NO_UPDATES");
 break;
 case HTTP_UPDATE_OK:
 USE_SERIAL.println("HTTP_UPDATE_OK");
 break;
 }
 }
}

• peeyush tekriwal: docs.google.com/document/d/…
• peeyush tekriwal: link to the code
• chrisl: Code, that is this short, should be copied directly into the question and formatted correctly as code by selecting it and pressing the {} button in the editor. I've done this for you now, but please remind it for the next question.
• peeyush tekriwal: Hey thanks. I did try to add the code in the question itself but it got weird and I couldn't do the formatting clearly so I gave a link.
• Juraj: what is String* updateURL = "XYZ.php";? you assign a pointer to constant char array to a pointer to String object. Where did you see something like this? It should be const char* updateURL = "XYZ.php"; or String updateURL = "XYZ.php";

Answer 1

String is included by Arduino.h. Before #include <Arduino.h> String is not defined. Move #include <Arduino.h> to the top of the file or remove it. If you remove it, the Arduino builder adds it.

• peeyush tekriwal: Thank you. It worked!/