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POCrash delete [ ] initialized char string
 

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    <p>After having fixed bugs coming from uninitialized pointers. an old bug still stand, it crashes in <code>stringclass::alloc()</code> if I delete mystring though we can handle or display it just before. It has been initialized so what happened this time?</p> <pre><code>void stringclass::alloc(long newsize) { if(memsize &lt; newsize) { cout &lt;&lt; "checkpoint 1\n"; if(mystring) delete [] mystring; cout &lt;&lt; "checkpoint 2\n"; memsize = newsize; mystring = new char[memsize]; mystring[0] = 0; length = 0; } } </code></pre> <p><strong>Full code :</strong></p> <pre><code>#include &lt;iostream&gt; using namespace std; #define DEFAULT_BREAKPOINT -1 #define DEFAULT_STARTPOINT -1 class stringclass { protected : inline bool success() { failbit = false; return true; } inline bool fail() { failbit = true; return false; } public : bool failbit; long memsize; long length; char * mystring; bool ins(const char * str, long startpoint, long breakpoint); inline long get_length() { if(mystring) length = strlen(mystring); return length;} inline long get_memsize() const { return memsize; } void reset(); void alloc(long newsize); void copy(const stringclass &amp; other); stringclass(); stringclass(const char str[]); stringclass(const stringclass &amp; other); ~stringclass(); friend ostream&amp; operator &lt;&lt; (ostream&amp; out, stringclass &amp; sc){out &lt;&lt; sc.mystring; return out;} }; void stringclass::copy(const stringclass &amp; other) { if(other.mystring == NULL) { reset(); return; } alloc(other.memsize); strcpy(mystring, other.mystring); length = other.length; } stringclass::stringclass() : mystring(NULL), memsize(0), length(0) { } stringclass::stringclass(const char str[]) : mystring(NULL), memsize(0), length(0) { if(str != NULL) { alloc(strlen(str) + 1); strcpy(mystring, str); length = strlen(mystring); } } stringclass::stringclass(const stringclass &amp; other) : mystring(NULL), memsize(0), length(0) { copy(other); } stringclass::~stringclass() { delete [] mystring; } void stringclass::reset() { if(mystring) delete [] mystring; mystring = NULL; length = 0; memsize = 0; } void stringclass::alloc(long newsize) { if(memsize &lt; newsize) { cout &lt;&lt; "checkpoint 1\n"; if(mystring) delete [] mystring; cout &lt;&lt; "checkpoint 2\n"; memsize = newsize; mystring = new char[memsize]; mystring[0] = 0; length = 0; } } bool stringclass::ins(const char * str, long startpoint = DEFAULT_STARTPOINT, long breakpoint = DEFAULT_BREAKPOINT) { if(startpoint == DEFAULT_STARTPOINT) startpoint = 0; if(breakpoint == DEFAULT_BREAKPOINT) breakpoint = startpoint; if(breakpoint &gt; length || breakpoint - startpoint &lt; 0) return fail(); if(str == NULL) return fail(); long str_length = strlen(str); long temp_size = 0; bool to_resize = false; if(length + str_length + 1 - (breakpoint - startpoint) &gt; memsize) { temp_size = (length + str_length + 1 - (breakpoint - startpoint)); to_resize = true; } else temp_size = memsize; char * temp = new char[temp_size]; long temp_i = 0; if(mystring) for(; temp_i &lt; startpoint; temp_i++) temp[temp_i] = mystring[temp_i]; for(long str_i = 0; str_i &lt; str_length; str_i++, temp_i++) temp[temp_i] = str[str_i]; if(mystring) for(long buf_i = breakpoint; buf_i &lt; memsize; buf_i++, temp_i++)temp[temp_i] = mystring[buf_i]; temp[temp_i] = 0; if(to_resize) alloc(temp_size); //empty for(long buf_i = 0; buf_i &lt; memsize; buf_i++) mystring[buf_i] = temp[buf_i]; if(temp) delete [] temp; length = strlen(mystring); return success(); } int main() { stringclass str = "Hello"; str.ins("rld", str.get_length()); cout &lt;&lt; str &lt;&lt; endl; str.ins(" the wo", 5); cout &lt;&lt; str &lt;&lt; endl; system("PAUSE"); return 0; } </code></pre>
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    1. This table or related slice is empty.
    1. USnomatchland
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    1. PO
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    1. COThis actually runs - http://ideone.com/60eXuI
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      1. USLuchian Grigore
    2. CO@LuchianGrigore: likely it is UB, so it can run for you and crash for others.
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      1. USybungalobill
 

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