Unknown type name 'IRsend' In the C file in simplesample_mqtt.c, which connects Arduino to the Azure IoT hub, I need to use the IRsend and IrRemoteESP8266 libraries to send an infrared signal with Azure IoT hub.

 #include &lt;IRremoteESP8266.h&gt;
 #include &lt;IRsend.h&gt;
 IRsend irsend(10); // An IR LED is controlled by GPIO pin 4 (D2)


I don't have any problem when I use this code in my main Arduino file. But when I use these includes in a C file (simplesample_mqtt.c), I get this error from line 3: "unknown type name 'IRsend'".



error full info : 

Arduino: 1.8.2 (Windows 10), Board: "NodeMCU 0.9 (ESP-12 Module), 80 MHz, 115200, 4M (3M SPIFFS)"

In file included from sketch\simplesample_mqtt.c:29:0:

C:\Program Files (x86)\Arduino\libraries\IRremoteESP8266\src/IRsend.h:29:1: error: unknown type name 'class'

class IRsend {

C:\Program Files (x86)\Arduino\libraries\IRremoteESP8266\src/IRsend.h:29:14: error: expected '=', ',', ';', 'asm' or 'attribute' before '{' token

class IRsend {

simplesample_mqtt.c:31: error: unknown type name 'IRsend'

IRsend irsend(10); // An IR LED is controlled by GPIO pin 4 (D2)


simplesample_mqtt.c:31: error: expected declaration specifiers or '...' before numeric constant

IRsend irsend(10); // An IR LED is controlled by GPIO pin 4 (D2)

exit status 1
unknown type name 'IRsend'

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I solved this problem. The reason for this is because main Arduino is c++ and simplesample_mqtt.c is c code and we have to use c++ code in c code: 

In main Arduino file you have to declare function like this : 

extern "C" void TurnOn();
void TurnOn()
{
    digitalWrite(RELAY_SONOFF, HIGH);     
    digitalWrite(LED_SONOFF, HIGH);
}


and use this function in c code:

void TurnOn();
EXECUTE_COMMAND_RESULT TurnOn(ContosoAnemometer* device)
{
    (void)device;
    TurnOn();
    (void)printf("Turning fan on.\r\n");
    return EXECUTE_COMMAND_SUCCESS;
}