Question

I am adding values into the combo box as a string. Below is my code.

Platform Windows XP and I am using Microsoft Visual Studio 2003

language C++

error encountered -> “Run-Time Check Failure #2 – Stack around the variable ‘buffer’ was corrupted.”

If I increase the size of the buffer to say 4 and above then I won’t get this error.

My question is not related to how to fix that error, but I am wondering why I got this error if buffer size = 2.

According to my logic I have given buffer size = 2 as char[0] will store the valve of char[1] = null terminated character.

Now since char can store values from 0 to 255 , I thought this should be ok as my inserted values are from 1 to 63 and then from 183 to 200.

CComboBox m_select_combo;
const unsigned int max_num_of_values = 63;

m_select_combo.AddString( "ALL" );

for( unsigned int i = 1; i <= max_num_of_values ; ++i )
{
    char buffer[2];
    std::string prn_select_c = itoa( i, buffer, 10 ); 
    m_select_combo.AddString( prn_select_c.c_str() );
}

const unsigned int max_num_of_high_sats = 202 ;

for( unsigned int i = 183; i <= max_num_of_high_sats ; ++i )
{
    char buffer[2];
    std::string prn_select_c = itoa( i, buffer, 10 ); 
    m_select_combo.AddString( prn_select_c.c_str() );
}

Could you guys please give me an idea as to what I’m not understanding?

Answer 1

itoa() zero-terminates it’s output, so when you call itoa(63, char[2], 10) it writes three characters 6, 3 and the terminating \0. But your buffer is only two characters long.

itoa() function is best avoided in favour of snprintf() or boost::lexical_cast<>().