IT公司100题-25-求字符串中的最长数字串

 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 }

$ ./a.exe
input a str contain num:
123dfasdf123123asdfasdf33333333333333asdfsdf221asdf2323
33333333333333