Question

I’m resizing an array. The resize (doubling the size) appears to work correctly, but when I send more text into the resized array, when it reaches what would have been the limit of the array before it was resized, I get a “Debug Assertion Failed! Expression: (L”Buffer is too small” && 0)” error. I’ve tried it a few different ways, always with the same result.

    static int ReadBufferSize, totalChars;    
    static char *ReadBuffer = NULL;
    ReadBuffer = (char *)malloc(ReadBufferSize);

    ...

    //Double buffer size.
    if((float)totalChars > (0.75f) * (float)ReadBufferSize)
    {
        char *tempBuffer = NULL;
        tempBuffer = (char *)malloc(2 * ReadBufferSize); 
        if(tempBuffer == NULL)
            free(tempBuffer);
        else
        {
            memcpy(tempBuffer,ReadBuffer,strlen(ReadBuffer)+1);
            free(ReadBuffer);
            ReadBuffer = tempBuffer;
            tempBuffer = NULL;
            ReadBufferSize *= 2;
        }
    }

For my testing, ReadBufferSize has been set initially to 85 characters. After the code resizing the array is executed, the text in ReadBuffer is still displayed on the screen. I type more characters and they are sent into the array, and from there, displayed on the screen. But when the number of characters reaches 85 characters, I get the “Debug Assertion Failed! Expression: (L”Buffer is too small” && 0)” error, when there should now be space for 170 characters. I’ve also tried the following.

//Double buffer size.
if((float)totalChars > (0.75f) * (float)ReadBufferSize)
{
    char* temp = 0;
    temp = new char[2 * ReadBufferSize];
    for(unsigned int i = 0; i < strlen(ReadBuffer); i++)
        temp[i] = ReadBuffer[i];
    temp[strlen(ReadBuffer)] = '\0';
    delete[] ReadBuffer;
    ReadBuffer = temp;
    temp = 0;
    ReadBufferSize *= 2;
}

I’ve also tried:

malloc(2 * ReadBufferSize * sizeof(char));

and:

strcpy_s(tempBuffer, strlen(ReadBuffer)+1, ReadBuffer);

Many thanks.

Answer 1

I figured it out. I was about to post some more of my code to give you more information when I noticed the problem. I had a “pageSize” variable that I had been using for the size of the array. Then when I wanted to start dynamically changing the size, I separated the array size from the page size by creating the “ReadBufferSize” variable. Unfortunately, I still had “pageSize” in the segment of code where I was putting characters into the array:

strcat_s(ReadBuffer, pageSize, keystroke);

I’ve now changed it to

strcat_s(ReadBuffer, ReadBufferSize, keystroke);

and everything seems to be working. Thanks to everyone for taking the time to look at this. I was fixated on the idea that the problem must be in the section of code for resizing the array, not elsewhere.