IT company 100 question-25-find the longest digit string in the string

Problem description:Implement a function to find the longest consecutive numeric string in the string. For example, input "12345cbf3456" and output "12345 ″. Function prototype: void conti_num_max (const char * SRC, char * DEST );

DeST saves the longest numeric string and returns void.

Analysis:Traverse the string and record the start position and length.

Code implementation:

 

 1 // 25.cc 2 #include <iostream> 3 #include <cstring> 4 using namespace std; 5  6 void conti_num_max(const char* src, char* dest) { 7     if (!src) { 8         *dest = ‘\0‘; 9         return;10     }11 12     size_t len = 0;13     size_t max_len = 0;14     const char* p = src;15     const char* p_start = NULL;16     while (*p != ‘\0‘) {17         if (*p >= ‘0‘ && *p <= ‘9‘)18             len++;19         else {20             if (len > max_len) {21                 max_len = len;22                 p_start = p - len;23             }24             len = 0;25         }26         p++;27     }28     strncpy(dest, p_start, max_len);29 }30 31 int main() {32     string s;33     cout << "input a str contain num:" << endl;34     getline(cin, s);35 36     char* dest = new char[s.size() + 1];37     conti_num_max(s.c_str(), dest);38     cout << dest << endl;39     return 0;40 }

 

Output:

$ ./a.exeinput a str contain num:123dfasdf123123asdfasdf33333333333333asdfsdf221asdf232333333333333333