array to string in usart peripheral

The USART IRQ allows you to receive and/or transmit a single character. You need to manage the data as it comes in. You really should not be spinning around waiting for additional characters, and outputting strings in the handler. You could use a line buffer, accumulating one character at a time, when you have sufficient, you can then call a processing routine. You could also use a ring/fifo buffering scheme.

//**************************************************************************************
char USART_GetChar(void)
{
while(USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == RESET); // Wait For input character
return((char)USART_ReceiveData(USART1));
}
//**************************************************************************************
void USART_PutChar(char ch)
{
while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET); // Wait for holding buffer empty
USART_SendData(USART1, ch);
}
//**************************************************************************************
void USART_PutString(char *s)
{
while(*s)
USART_PutChar(*s++);
}
//**************************************************************************************
void USART_PutDecimal(unsigned int i)
{
char String[16];
char *s = String + sizeof(String);
*--s = 0; // NUL
do
{
*--s = '0' + (char)(i % 10);
i /= 10;
}
while(i);
USART_PutString(s);
}
//**************************************************************************************

So for the following pseudo code

''I'd generally recommend learning C thoroughly on a PC platform before migrating to embedded.''

http://blog.antronics.co.uk/2011/08/08/so-youre-thinking-of-starting-with-c/

''I'd generally recommend learning C thoroughly on a PC platform before migrating to embedded.''

I grew up with DOS PC's which were rather slow and memory/storage constrained, and before that 8-bit micros. The temptation to load a 1MB array of numbers just wasn't going to happen.

''... printf(), malloc(), and all those OS services that don't exist anywhere else''

''It creates a mindset that's limited to the usual trivial examples in classroom books''