String to Integer (atoi), integeratoi

String to Integer (atoi), integeratoi

Implement atoi to convert a string to an integer.

Hint:Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.

Notes:It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.

Update ):
The signature ofC++Function had been updated. If you still see your function signature acceptsconst char *Argument, please click the reload button to reset your code definition.

Class Solution {public: // convert string to int. Be sure to judge that the Int range is exceeded int myAtoi (string str) {if (str = ") return 0; // str. erase (0, str. find_first_not_of (''); str. erase (str. find_last_not_of ('') + 1); int I = 0, len = str. length (), sign = 1; while (I <len & str [I] = '') I ++; if (I = len) return 0; if (str [I] = '+') {sign = 1; I ++;} else if (str [I] = '-') {sign =-1; I ++;} // The conversion result may be out of the int range. long ret = 0; (; I <len; I ++) {if (str [I] <'0' | str [I]> '9') break; ret = ret * 10 + (str [I]-'0'); if (ret> INT_MAX) break;} ret * = sign; if (ret> INT_MAX) return INT_MAX; if (ret <INT_MIN) return INT_MIN; return ret ;}};

Note:

The erase function is prototype as follows:
(1) string & erase (size_t pos = 0, size_t n = npos );
(2) iterator erase (iterator position );
(3) iterator erase (iterator first, iterator last );
That is to say, there are three usage methods:
(1) erase (pos, n); Delete n characters starting from pos. For example, erase (0, 1) is to delete the first character.
(2) erase (position); delete a character at position (position is a string type iterator)
(3) erase (first, last); Delete the characters from first to last (both first and last are iterators)

The following is the definition of library functions:

stl: template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,           typename _Pointer = _Tp*, typename _Reference = _Tp&>    struct iterator    {      /// One of the @link iterator_tags tag types@endlink.      typedef _Category  iterator_category;      /// The type "pointed to" by the iterator.      typedef _Tp        value_type;      /// Distance between iterators is represented as this type.      typedef _Distance  difference_type;      /// This type represents a pointer-to-value_type.      typedef _Pointer   pointer;      /// This type represents a reference-to-value_type.      typedef _Reference reference;    };string: iterator      erase(iterator __first, iterator __last); #if __cplusplus >= 201103L      /**       *  @brief  Remove the last character.       *       *  The string must be non-empty.       */      void      pop_back() // FIXME C++11: should be noexcept.      { erase(size()-1, 1); }