atoi

问题 What is the difference between atoi and stoi ? I know, std::string my_string = \"123456789\"; In order to convert that string to an integer, you’d have to do the following: const char* my_c_string = my_string.c_str(); int my_integer = atoi(my_c_string); C++11 offers a succinct replacement: std::string my_string = \"123456789\"; int my_integer = std::stoi(my_string); 1). Are there any other differences between the two? 2). Efficiency and performance wise which one is better? 3). Which is safer

问题 I don\'t understand the results of the following C code. main() { char s[] = \"AAA\"; advanceString(s); } void advanceString(p[3]) { int val = atoi(p); printf(\"The atoi val is %d\\n\",val); } Here the atoi value is shown as 0, but I could not figure out the exact reason. As per my understanding, it should be the summation of decimal equivalent of each values in the array? Please correct me if I am wrong. 回答1: atoi() converts a string representation of an integer into its value. It will not

问题 When using the function atoi (or strtol or similar functions for that matter), how can you tell if the integer conversion failed or if the C-string that was being converted was a 0 ? For what I\'m doing, 0 is an acceptable value and the C-string being converted may contain any number of 0 s. It may also have leading whitespace. 回答1: For C++11 and later: The go-to function for string-to-integer conversion is now stoi, which takes a string and returns an int , or throws an exception on error.

问题 http://www.cplusplus.com/reference/clibrary/cstdlib/atoi/ Return Value On success, the function returns the converted integral number as an int value. If no valid conversion could be performed, a zero value is returned. If the correct value is out of the range of representable values, INT_MAX or INT_MIN is returned. So how I differ between atoi(\"poop\") and atoi(\"0\") and atoi(\"0000000\") Yes I can loop and check for all zeroes in case I get 0 result, but isn\'t there a better way? Notice:

问题 I am trying to find out if there is an alternative way of converting string to integer in C. I regularly pattern the following in my code. char s[] = \"45\"; int num = atoi(s); So, is there a better way or another way? 回答1: There is strtol which is better IMO. Also I have taken a liking in strtonum, so use it if you have it (but remember it's not portable): long long strtonum(const char *nptr, long long minval, long long maxval, const char **errstr); EDIT You might also be interested in