How to write a function inside a function

Hi there,

I’m trying to get a led to respond to a certain temperature (data obtained from Wunderground). Where do I write the code?

I tried it with:

void setled {


if (temp_c <= 10) {
    Serial.println("De temperatuur is gelijk aan of beneden 10 graden");
    digitalWrite(ledPin, HIGH);
  }

  else {
    digitalWrite(ledPin, LOW);
  }
}

But I keep getting the error: variable or field “setled” declared void

Here’s my complete code:

#include <ESP8266WiFi.h>
#ifndef min
#define min(x,y) (((x)<(y))?(x):(y))
#endif
#ifndef max
#define max(x,y) (((x)>(y))?(x):(y))
#endif
#include <ArduinoJson.h>
int ledPin = D0;


const char SSID[]     = "*********";
const char PASSWORD[] = "*********";

// Use your own API key by signing up for a free developer account.
// http://www.wunderground.com/weather/api/
#define WU_API_KEY "***************"

// Specify your favorite location one of these ways.
//#define WU_LOCATION "NL/AMSTERDAM"

// US ZIP code
//#define WU_LOCATION ""
//#define WU_LOCATION "90210"

// Country and city
#define WU_LOCATION "Netherlands/Amsterdam"
//
// 5 minutes between update checks. The free developer account has a limit
// on the  number of calls so don't go wild.
#define DELAY_NORMAL    (5*60*1000)
// 20 minute delay between updates after an error
#define DELAY_ERROR     (20*60*1000)

#define WUNDERGROUND "api.wunderground.com"

// HTTP request
const char WUNDERGROUND_REQ[] =
  "GET /api/" WU_API_KEY "/conditions/q/" WU_LOCATION ".json HTTP/1.1\r\n"
  "User-Agent: ESP8266/0.1\r\n"
  "Accept: */*\r\n"
  "Host: " WUNDERGROUND "\r\n"
  "Connection: close\r\n"
  "\r\n";

void setup()
{
  
  Serial.begin(115200);

  // We start by connecting to a WiFi network
  Serial.println();
  Serial.println();
  Serial.print(F("Connecting to "));
  Serial.println(SSID);

  WiFi.begin(SSID, PASSWORD);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(F("."));
  }

  Serial.println();
  Serial.println(F("WiFi connected"));
  Serial.println(F("IP address: "));
  Serial.println(WiFi.localIP());

  pinMode(ledPin, OUTPUT);
}

static char respBuf[4096];

void loop()
{
 int setled();
  // TODO check for disconnect from AP

  // Open socket to WU server port 80
  Serial.print(F("Connecting to "));
  Serial.println(WUNDERGROUND);

  // Use WiFiClient class to create TCP connections
  WiFiClient httpclient;
  const int httpPort = 80;
  if (!httpclient.connect(WUNDERGROUND, httpPort)) {
    Serial.println(F("connection failed"));
    delay(DELAY_ERROR);
    return;
  }

  // This will send the http request to the server
  Serial.print(WUNDERGROUND_REQ);
  httpclient.print(WUNDERGROUND_REQ);
  httpclient.flush();

  // Collect http response headers and content from Weather Underground
  // HTTP headers are discarded.
  // The content is formatted in JSON and is left in respBuf.
  int respLen = 0;
  bool skip_headers = true;
  while (httpclient.connected() || httpclient.available()) {
    if (skip_headers) {
      String aLine = httpclient.readStringUntil('\n');
      //Serial.println(aLine);
      // Blank line denotes end of headers
      if (aLine.length() <= 1) {
        skip_headers = false;
      }
    }
    else {
      int bytesIn;
      bytesIn = httpclient.read((uint8_t *)&respBuf[respLen], sizeof(respBuf) - respLen);
      Serial.print(F("bytesIn ")); Serial.println(bytesIn);
      if (bytesIn > 0) {
        respLen += bytesIn;
        if (respLen > sizeof(respBuf)) respLen = sizeof(respBuf);
      }
      else if (bytesIn < 0) {
        Serial.print(F("read error "));
        Serial.println(bytesIn);
      }
    }
    delay(1);
  }
  httpclient.stop();

  if (respLen >= sizeof(respBuf)) {
    Serial.print(F("respBuf overflow "));
    Serial.println(respLen);
    delay(DELAY_ERROR);
    return;
  }
  // Terminate the C string
  respBuf[respLen++] = '\0';
  Serial.print(F("respLen "));
  Serial.println(respLen);
  //Serial.println(respBuf);

  if (showWeather(respBuf)) {
    delay(DELAY_NORMAL);
  }
  else {
    delay(DELAY_ERROR);
  }
}

bool showWeather(char *json)
{
  StaticJsonBuffer<3 * 1024> jsonBuffer;

  // Skip characters until first '{' found
  // Ignore chunked length, if present
  char *jsonstart = strchr(json, '{');
  //Serial.print(F("jsonstart ")); Serial.println(jsonstart);
  if (jsonstart == NULL) {
    Serial.println(F("JSON data missing"));
    return false;
  }
  json = jsonstart;

  // Parse JSON
  JsonObject& root = jsonBuffer.parseObject(json);
  if (!root.success()) {
    Serial.println(F("jsonBuffer.parseObject() failed"));
    return false;
  }

  // Extract weather info from parsed JSON
  JsonObject& current = root["current_observation"];
  const float temp_f = current["temp_f"];
  Serial.print(temp_f, 1); Serial.print(F(" F, "));
  const float temp_c = current["temp_c"];
  Serial.print(temp_c, 1); Serial.print(F(" C, "));
  const char *humi = current[F("relative_humidity")];
  Serial.print(humi);   Serial.println(F(" RH"));
  const char *weather = current["weather"];
  Serial.println(weather);
  const char *pressure_mb = current["pressure_mb"];
  Serial.println(pressure_mb);
  const char *observation_time = current["observation_time_rfc822"];
  Serial.println(observation_time);

  // Extract local timezone fields
  const char *local_tz_short = current["local_tz_short"];
  Serial.println(local_tz_short);
  const char *local_tz_long = current["local_tz_long"];
  Serial.println(local_tz_long);
  const char *local_tz_offset = current["local_tz_offset"];
  Serial.println(local_tz_offset);
  return true;



}
void setled {


if (temp_c <= 10) {
    Serial.println("De temperatuur is gelijk aan of beneden 10 graden");
    digitalWrite(ledPin, HIGH);
  }

  else {
    digitalWrite(ledPin, LOW);
  }
}
void setled

Does that look like the start of any other function declaration you have seen, even the others in your program such as loop() ?

 int setled();

I assume that this is an attempt to call the setled() function. What is that type specifier doing in front of the function call ? Compare it with your calls to Serial.print() for example

Fix those two problems and try compiling again. Come back if you still have problems and post your updated code in your reply

Thanks for helping!

Sorry, very slovenly… Was trying several things at the same time.

I now fixed these two issues.

This is now my code but I get the error: ‘temp_c’ was not declared in this scope. How can I get the ‘temp_c’ inside this function?

/****************************
  The MIT License (MIT)
  Copyright (c) 2015 by bbx10node@gmail.com
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
******************************/

#include <ESP8266WiFi.h>
#ifndef min
#define min(x,y) (((x)<(y))?(x):(y))
#endif
#ifndef max
#define max(x,y) (((x)>(y))?(x):(y))
#endif
#include <ArduinoJson.h>
int ledPin = D0;


const char SSID[]     = "iot";
const char PASSWORD[] = "amsterdam";

// Use your own API key by signing up for a free developer account.
// http://www.wunderground.com/weather/api/
#define WU_API_KEY "90cbcd9977f245d6"

// Specify your favorite location one of these ways.
//#define WU_LOCATION "NL/AMSTERDAM"

// US ZIP code
//#define WU_LOCATION ""
//#define WU_LOCATION "90210"

// Country and city
#define WU_LOCATION "Netherlands/Amsterdam"
//
// 5 minutes between update checks. The free developer account has a limit
// on the  number of calls so don't go wild.
#define DELAY_NORMAL    (5*60*1000)
// 20 minute delay between updates after an error
#define DELAY_ERROR     (20*60*1000)

#define WUNDERGROUND "api.wunderground.com"

// HTTP request
const char WUNDERGROUND_REQ[] =
  "GET /api/" WU_API_KEY "/conditions/q/" WU_LOCATION ".json HTTP/1.1\r\n"
  "User-Agent: ESP8266/0.1\r\n"
  "Accept: */*\r\n"
  "Host: " WUNDERGROUND "\r\n"
  "Connection: close\r\n"
  "\r\n";

void setup()
{
  
  Serial.begin(115200);

  // We start by connecting to a WiFi network
  Serial.println();
  Serial.println();
  Serial.print(F("Connecting to "));
  Serial.println(SSID);

  WiFi.begin(SSID, PASSWORD);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(F("."));
  }

  Serial.println();
  Serial.println(F("WiFi connected"));
  Serial.println(F("IP address: "));
  Serial.println(WiFi.localIP());

  pinMode(ledPin, OUTPUT);
}

static char respBuf[4096];

void loop()
{
 int setled();
  // TODO check for disconnect from AP

  // Open socket to WU server port 80
  Serial.print(F("Connecting to "));
  Serial.println(WUNDERGROUND);

  // Use WiFiClient class to create TCP connections
  WiFiClient httpclient;
  const int httpPort = 80;
  if (!httpclient.connect(WUNDERGROUND, httpPort)) {
    Serial.println(F("connection failed"));
    delay(DELAY_ERROR);
    return;
  }

  // This will send the http request to the server
  Serial.print(WUNDERGROUND_REQ);
  httpclient.print(WUNDERGROUND_REQ);
  httpclient.flush();

  // Collect http response headers and content from Weather Underground
  // HTTP headers are discarded.
  // The content is formatted in JSON and is left in respBuf.
  int respLen = 0;
  bool skip_headers = true;
  while (httpclient.connected() || httpclient.available()) {
    if (skip_headers) {
      String aLine = httpclient.readStringUntil('\n');
      //Serial.println(aLine);
      // Blank line denotes end of headers
      if (aLine.length() <= 1) {
        skip_headers = false;
      }
    }
    else {
      int bytesIn;
      bytesIn = httpclient.read((uint8_t *)&respBuf[respLen], sizeof(respBuf) - respLen);
      Serial.print(F("bytesIn ")); Serial.println(bytesIn);
      if (bytesIn > 0) {
        respLen += bytesIn;
        if (respLen > sizeof(respBuf)) respLen = sizeof(respBuf);
      }
      else if (bytesIn < 0) {
        Serial.print(F("read error "));
        Serial.println(bytesIn);
      }
    }
    delay(1);
  }
  httpclient.stop();

  if (respLen >= sizeof(respBuf)) {
    Serial.print(F("respBuf overflow "));
    Serial.println(respLen);
    delay(DELAY_ERROR);
    return;
  }
  // Terminate the C string
  respBuf[respLen++] = '\0';
  Serial.print(F("respLen "));
  Serial.println(respLen);
  //Serial.println(respBuf);

  if (showWeather(respBuf)) {
    delay(DELAY_NORMAL);
  }
  else {
    delay(DELAY_ERROR);
  }
}

bool showWeather(char *json)
{
  StaticJsonBuffer<3 * 1024> jsonBuffer;

  // Skip characters until first '{' found
  // Ignore chunked length, if present
  char *jsonstart = strchr(json, '{');
  //Serial.print(F("jsonstart ")); Serial.println(jsonstart);
  if (jsonstart == NULL) {
    Serial.println(F("JSON data missing"));
    return false;
  }
  json = jsonstart;

  // Parse JSON
  JsonObject& root = jsonBuffer.parseObject(json);
  if (!root.success()) {
    Serial.println(F("jsonBuffer.parseObject() failed"));
    return false;
  }

  // Extract weather info from parsed JSON
  JsonObject& current = root["current_observation"];
  const float temp_f = current["temp_f"];
  Serial.print(temp_f, 1); Serial.print(F(" F, "));
  const float temp_c = current["temp_c"];
  Serial.print(temp_c, 1); Serial.print(F(" C, "));
  const char *humi = current[F("relative_humidity")];
  Serial.print(humi);   Serial.println(F(" RH"));
  const char *weather = current["weather"];
  Serial.println(weather);
  const char *pressure_mb = current["pressure_mb"];
  Serial.println(pressure_mb);
  const char *observation_time = current["observation_time_rfc822"];
  Serial.println(observation_time);

  // Extract local timezone fields
  const char *local_tz_short = current["local_tz_short"];
  Serial.println(local_tz_short);
  const char *local_tz_long = current["local_tz_long"];
  Serial.println(local_tz_long);
  const char *local_tz_offset = current["local_tz_offset"];
  Serial.println(local_tz_offset);
  return true;





}

void setled() {
if (temp_c <= 11) {
    Serial.println("De temperatuur is gelijk aan of beneden 10 graden");
    digitalWrite(ledPin, HIGH);
  }

  else {
    digitalWrite(ledPin, LOW);
  }
{
 int setled();

This is defining a function prototype for a function. That is a strange thing to do inside another function. It is NOT calling an existing function.

  StaticJsonBuffer<3 * 1024> jsonBuffer;

Which Arduino are you using? Using 3072 bytes on a 328-based Arduino is NOT going to happen.

How can I get the ‘temp_c’ inside this function?

Just like analogWrite() gets a pin number or a PWM value. Just like digitalRead() gets a pin number.

You define the function to take an argument. You call the function with an argument.

You can't put function definitions inside other function definitions. Any function can call any other because they are all defined at the top level. A function can even call itself although that has limited usefulness on an Arduino.

To organize functions properly, so that you don't have a mess of everything making changes to things that it shouldn't, you can organize the functions into classes. That's the start of object-oriented programming. Most Arduino libraries are written as classes.