How to compare uint8_t array to a string in C?

问题

I have an input which comes over UART.

uint8_t uartRX_data[UART_RX_BUF_SIZE]="";

I need to pass this data to a function. And, in this function I want to compare it with predefined strings like:

char RESP_OK[]                  = "OK";
char RESP_ERROR[]               = "ERROR";
char RESP_FAIL[]                = "FAIL";

What is the easiest way to do that?

EDIT: My problem is only about the data comparison and data passing to a function.

回答1:

As long as the string in uartRX_data is NULL terminated you should be able to use strcmp like so:

if (strcmp((const char *)uartRX_data, RESP_OK) == 0)
{
  // handle OK
}
else if (strcmp((const char *)uartRX_data, RESP_ERROR) == 0)
{
  // handle ERROR
}
else if (strcmp((const char *)uartRX_data, RESP_FAIL) == 0)
{
  // handle FAIL
}
else
{
  // handle unknown response
}

回答2:

Most conversions between the types char, signed char, unsigned char, int8_t and uint8_t can be regarded as safe. These are the character types and come with various special exceptions that make them more "rugged" than other types.

Specifically, the character types:

Cannot be misaligned.
Cannot contain padding bits or trap representations.
Have exceptions from the effective type/strict aliasing rules.
Are always of size 1 byte.

Meaning you can do all manner of wild conversions between different character types. With a few exceptions:

When going from unsigned to signed types the data may not necessarily fit and you'll overwrite the sign bit. This will potentially cause bugs.
It is dangerous to "cast away" const or volatile qualifiers, if present.

Therefore it is safe to convert from uint8_t* to char* and de-reference the data as another type, (char*)uartRX_data. Especially if you know that the uint8_t array contains valid 7 bit characters only with MSB never set, and with a null termination in the end of the array.

来源：https://stackoverflow.com/questions/55967430/how-to-compare-uint8-t-array-to-a-string-in-c

标签

string

uint8t