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  1. #include <stdio.h>
  2. #include <string.h>
  3.  
  4. class mystr {
  5. private:
  6.     char *str;
  7.     size_t len, buflen;
  8.     int *refcount;
  9.  
  10. public:
  11.     const char *c_str() const { return str; }
  12.     size_t length() const { return len; }
  13.  
  14.     mystr() {
  15.         str = NULL;
  16.         *this = "";
  17.     }
  18.  
  19.     mystr(const char *s) {
  20.         str = NULL;
  21.         *this = s;
  22.     }
  23.  
  24.     mystr(const mystr &s) {
  25.         str = NULL;
  26.         *this = s;
  27.     }
  28.  
  29.     ~mystr() {
  30.         unset(str);
  31.     }
  32.  
  33.     void printn() const {
  34.         printf("%s\n", str);
  35.     }
  36.  
  37. private:
  38.     void set(const char *s, size_t newlen) {
  39.         char *old = str;
  40.         len = newlen;
  41.         if (!old || buflen < len) {
  42.             if (!old) buflen = 16;
  43.             while (buflen < len)
  44.                 buflen += buflen;
  45.             str = new char[buflen + 1];
  46.         } else if (*refcount > 1) {
  47.             str = new char[buflen + 1];
  48.         }
  49.         if (str != s) strcpy(str, s);
  50.         if (old != str) {
  51.             unset(old);
  52.             refcount = new int(1);
  53.         }
  54.     }
  55.  
  56.     void unset(char *str) {
  57.         if (str && --*refcount == 0) {
  58.             delete refcount;
  59.             delete[] str;
  60.         }
  61.     }
  62.  
  63. public:
  64.     mystr &operator+=(const char *s) {
  65.         int oldlen = len;
  66.         set(str, len + strlen(s));
  67.         strcpy(&str[oldlen], s);
  68.         return *this;
  69.     }
  70.  
  71.     mystr &operator+=(const mystr &s) {
  72.         int oldlen = len;
  73.         set(str, len + s.len);
  74.         strcpy(&str[oldlen], s.str);
  75.         return *this;
  76.     }
  77.  
  78.     mystr &operator=(const char *s) {
  79.         set(s, strlen(s));
  80.         return *this;
  81.     }
  82.  
  83.     mystr &operator=(const mystr &s) {
  84.         unset(str);
  85.         str = s.str;
  86.         len = s.len;
  87.         buflen = s.buflen;
  88.         ++*(refcount = s.refcount);
  89.         return *this;
  90.     }
  91.  
  92.     mystr substr(int start, int len) const {
  93.         mystr ret;
  94.         ret.set("", len);
  95.         strncpy(ret.str, &str[start], len);
  96.         ret.str[len] = 0;
  97.         return ret;
  98.     }
  99. };
  100.  
  101. mystr operator+(const mystr &s1, const mystr &s2) {
  102.     mystr ret = s1;
  103.     ret += s2;
  104.     return ret;
  105. }
  106.  
  107. int main() {
  108.     mystr s1 = "abc", s2 = s1;
  109.     s1 += "def";
  110.     printf("s1[%d]%s\n", s1.length(), s1.c_str());
  111.     printf("s2[%d]%s\n", s2.length(), s2.c_str());
  112. }
  113.  
Success #stdin #stdout 0s 2816KB
comments (?)
stdin
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Standard input is empty
stdout
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s1[6]abcdef
s2[3]abc
https://ideone.com/X1nO6c
language:
C++ 4.3.2 (gcc-4.3.2)
created:
9 years ago
visibility:
public

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