Get hour with ctime (time library with ESP8266)

Question

#include <ESP8266WiFi.h>
#include <time.h>
const char* ssid = "";
const char* password = "";
int timezone = 3;
int dst = 0;
void setup() {
 Serial.begin(115200);
 Serial.setDebugOutput(true);
 WiFi.mode(WIFI_STA);
 WiFi.begin(ssid, password);
 Serial.println("\nConnecting to WiFi");
 while (WiFi.status() != WL_CONNECTED) {
 Serial.print(".");
 delay(1000);
 }
 configTime(timezone * 3600, dst * 0, "pool.ntp.org", "time.nist.gov");
 Serial.println("\nWaiting for time");
 while (!time(nullptr)) {
 Serial.print(".");
 delay(1000);
 }
 Serial.println("");
}
void loop() {
 time_t now = time(nullptr);
 Serial.println(ctime(&now));
 delay(1000);
}

This is my code, but it shows the time like this: Sun Jul 23 15:21:12 2017. But what I want it to do is to only show the current hour, not everything. Is it possible to do that?

• Mikael Patel: Use gmtime() or localtime() instead of ctime(). Print the hour field tm_hour in the struct tm.
• Michel Keijzers: Welcome to the site. Next time for aligning code, select code and press ctrl+k
• unclenorton: @MikaelPatel I am a beginner at this, could you please give me an example of how it should look like?
• unclenorton: @MikaelPatel Okay i tried this Serial.println(gmtime(tm_hour)); but i get an error "'tm_hour' was not declared in this scope"
• Mikael Patel: Here is an example of gmtime() and the struct tm; cplusplus.com/reference/ctime/gmtime

Answer 1

The easiest way is to use the standard function localtime() or gmtime() and the struct tm.

void loop() {
 time_t now;
 struct tm * timeinfo;
 time(&now);
 timeinfo = localtime(&now); 
 Serial.println(timeinfo->tm_hour);
 delay(1000);
}