int atoi

int atoi(const char *__s) __ATTR_PURE__

The atoi() function converts the initial portion of the string pointed to by s to integer representation. In contrast to

 (int)strtol(s, (char **)NULL, 10); 

this function does not detect overflow (errno is not changed and the result value is not predictable), uses smaller memory (flash and stack) and works more quickly.