How can I get the mean IRQ that using STM32 systems

I have a question about EXTI0_IRQn What does it mean "IRQn"? How can i spell it word by word?

I've tried to get it on Google but I couldn't.

All the manufacturers of microcontroller invent some kind of abbreviation system, unfortunately there is no real standard. But you will get used to it with growing experience, and because of your coming expectations you will quickly interpret such constants in the almost correct sense.

EXTI0_IQRn it made up of multiple parts:

• EXT is for "external": The source of this interrupt is an external circuit, which signals its request to interrupt the processor via a GPIO pin.
• I is for "interrupt", just to signal that it is talked about interrupts here.
• 0 is the number of the interrupt line 0. It has its own interrupt vector, if I found the correct reference manual.
• I is again "interrupt", and in combination with:
• RQ for "request" means the signal that requests the interrupt. This abbreviation "IRQ" for "interrupt request" is really common across many microcontrollers.
• n stands most probably for "number". As said above, the STM32 has multiple interrupt vectors, collected in an array of jump target addresses. In C you would call these "function pointers". The symbol EXTI0_IRQn is defined as the index into this array.