STM32 C : atoi converts part of string which is not an argument

Question

I have parsed some date and time from GPS receiver. And need to convert them from string to int:

char year[4] = "2014";
char month[2] = "01";
char day[2] = "24";
char hour[2] ="12";
char minute[2] = "58";
char second[2] = "39";

GPS_current_year = atoi(year);
GPS_current_month = atoi(month);
GPS_current_day = atoi(day);
GPS_current_hour = atoi(hour);
GPS_current_minute = atoi(minute);
GPS_current_second = atoi(second);

After executing these the results are:

Somehow part of minutes string is converted when converting hour string. Same with minutes and seconds.

The strings are placed side by side in the memory.

If I change the sequence of defining strings then seconds may be added to years etc.

Questions:

• What may cause this error?
• Is there any way to avoid this error with using atoi?

I know that I can convert using a loop one char at a time. Just trying to find why is it not working.

Answer 1

Besides the missing quotes around the strings your char array's size should be defined to hold one more char the EOS (end of string a binary zero).

Since the memory representation would be e.g. "2014\0"

char year[4+1] = "2014";

Answer 2

Suggest not trying to define the string size as 4 or 5.
Let the compiler determine the string size.

char year[] = "2014";

In this case, the compiler will make year with a size of 5 initialized with '2', '0', '1', '4', '\0'.

OP's defining the size as 4 resulted in a size of 4-char array without a terminating '\0', which not being a string, create problems with atoi(year).

Answer 3

You forgot quotes in the strings:

char year[4] = "2014";

Answer 4

atoi() converts string to integer. But you are giving non string values to your string variables. Change your code to

char year[5] = "2014";
char month[3] = "01";
char day[3] = "24";
char hour[3] ="12";
char minute[3] = "58";
char second[3] = "39";